apply prefer_asserts_in_initializer_list lint (#10489)

packages/flutter/lib/src/rendering/animated_size.dart

@@ -39,10 +39,11 @@ class RenderAnimatedSize extends RenderAligningShiftedBox {
     Curve curve: Curves.linear,
     FractionalOffset alignment: FractionalOffset.center,
     RenderBox child,
-  }) : _vsync = vsync, super(child: child, alignment: alignment) {
+  }) : assert(vsync != null),
-    assert(vsync != null);
+       assert(duration != null),
-    assert(duration != null);
+       assert(curve != null),
-    assert(curve != null);
+       _vsync = vsync,
+       super(child: child, alignment: alignment) {
     _controller = new AnimationController(
       vsync: vsync,
       duration: duration,

packages/flutter/lib/src/rendering/custom_layout.dart

@@ -268,8 +268,8 @@ class RenderCustomMultiChildLayoutBox extends RenderBox
   RenderCustomMultiChildLayoutBox({
     List<RenderBox> children,
     @required MultiChildLayoutDelegate delegate
-  }) : _delegate = delegate {
+  }) : assert(delegate != null),
-    assert(delegate != null);
+       _delegate = delegate {
     addAll(children);
   }
 

packages/flutter/lib/src/rendering/editable.dart

@@ -71,16 +71,16 @@ class RenderEditable extends RenderBox {
     @required ViewportOffset offset,
     this.onSelectionChanged,
     this.onCaretChanged,
-  }) : _textPainter = new TextPainter(text: text, textAlign: textAlign, textScaleFactor: textScaleFactor),
+  }) : assert(maxLines != null),
+       assert(textScaleFactor != null),
+       assert(offset != null),
+       _textPainter = new TextPainter(text: text, textAlign: textAlign, textScaleFactor: textScaleFactor),
        _cursorColor = cursorColor,
        _showCursor = showCursor ?? new ValueNotifier<bool>(false),
        _maxLines = maxLines,
        _selection = selection,
        _offset = offset {
     assert(_showCursor != null);
-    assert(maxLines != null);
-    assert(textScaleFactor != null);
-    assert(offset != null);
     assert(!_showCursor.value || cursorColor != null);
     _tap = new TapGestureRecognizer()
       ..onTapDown = _handleTapDown

packages/flutter/lib/src/rendering/flex.dart

@@ -201,15 +201,15 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
     MainAxisAlignment mainAxisAlignment: MainAxisAlignment.start,
     CrossAxisAlignment crossAxisAlignment: CrossAxisAlignment.center,
     TextBaseline textBaseline
-  }) : _direction = direction,
+  }) : assert(direction != null),
+       assert(mainAxisAlignment != null),
+       assert(mainAxisSize != null),
+       assert(crossAxisAlignment != null),
+       _direction = direction,
        _mainAxisAlignment = mainAxisAlignment,
        _mainAxisSize = mainAxisSize,
        _crossAxisAlignment = crossAxisAlignment,
        _textBaseline = textBaseline {
-    assert(direction != null);
-    assert(mainAxisAlignment != null);
-    assert(mainAxisSize != null);
-    assert(crossAxisAlignment != null);
     addAll(children);
   }
 

packages/flutter/lib/src/rendering/flow.dart

@@ -182,8 +182,8 @@ class RenderFlow extends RenderBox
   RenderFlow({
     List<RenderBox> children,
     @required FlowDelegate delegate
-  }) : _delegate = delegate {
+  }) : assert(delegate != null),
-    assert(delegate != null);
+       _delegate = delegate {
     addAll(children);
   }
 

packages/flutter/lib/src/rendering/layer.dart

@@ -643,11 +643,9 @@ class PhysicalModelLayer extends ContainerLayer {
     @required this.clipRRect,
     @required this.elevation,
     @required this.color,
-  }) {
+  }) : assert(clipRRect != null),
-    assert(clipRRect != null);
+       assert(elevation != null),
-    assert(elevation != null);
+       assert(color != null);
-    assert(color != null);
-  }
 
   /// The rounded-rect to clip in the parent's coordinate system.
   ///

packages/flutter/lib/src/rendering/object.dart

@@ -57,10 +57,9 @@ typedef void PaintingContextCallback(PaintingContext context, Offset offset);
 /// not hold a reference to the canvas across operations that might paint
 /// child render objects.
 class PaintingContext {
-  PaintingContext._(this._containerLayer, this._paintBounds) {
+  PaintingContext._(this._containerLayer, this._paintBounds)
-    assert(_containerLayer != null);
+    : assert(_containerLayer != null),
-    assert(_paintBounds != null);
+      assert(_paintBounds != null);
-  }
 
   final ContainerLayer _containerLayer;
   final Rect _paintBounds;
@@ -664,19 +663,17 @@ abstract class _SemanticsFragment {
     this.annotator,
     List<_SemanticsFragment> children,
     this.dropSemanticsOfPreviousSiblings,
-  }) {
+  }) : assert(renderObjectOwner != null),
-    assert(renderObjectOwner != null);
+       assert(() {
-    _ancestorChain = <RenderObject>[renderObjectOwner];
+         if (children == null)
-    assert(() {
+           return true;
-      if (children == null)
+         final Set<_SemanticsFragment> seenChildren = new Set<_SemanticsFragment>();
-        return true;
+         for (_SemanticsFragment child in children)
-      final Set<_SemanticsFragment> seenChildren = new Set<_SemanticsFragment>();
+           assert(seenChildren.add(child)); // check for duplicate adds
-      for (_SemanticsFragment child in children)
+         return true;
-        assert(seenChildren.add(child)); // check for duplicate adds
+       }),
-      return true;
+       _ancestorChain = <RenderObject>[renderObjectOwner],
-    });
+       _children = children ?? const <_SemanticsFragment>[];
-    _children = children ?? const <_SemanticsFragment>[];
-  }
 
   final SemanticsAnnotator annotator;
   bool dropSemanticsOfPreviousSiblings;
@@ -722,10 +719,12 @@ class _CleanSemanticsFragment extends _SemanticsFragment {
   _CleanSemanticsFragment({
     @required RenderObject renderObjectOwner,
     bool dropSemanticsOfPreviousSiblings,
-  }) : super(renderObjectOwner: renderObjectOwner, dropSemanticsOfPreviousSiblings: dropSemanticsOfPreviousSiblings) {
+  }) : assert(renderObjectOwner != null),
-    assert(renderObjectOwner != null);
+       assert(renderObjectOwner._semantics != null),
-    assert(renderObjectOwner._semantics != null);
+       super(
-  }
+         renderObjectOwner: renderObjectOwner,
+         dropSemanticsOfPreviousSiblings: dropSemanticsOfPreviousSiblings
+       );
 
   @override
   Iterable<SemanticsNode> compile({ _SemanticsGeometry geometry, SemanticsNode currentSemantics, SemanticsNode parentSemantics }) sync* {
@@ -903,10 +902,13 @@ class _ForkingSemanticsFragment extends _SemanticsFragment {
     RenderObject renderObjectOwner,
     @required Iterable<_SemanticsFragment> children,
     bool dropSemanticsOfPreviousSiblings,
-  }) : super(renderObjectOwner: renderObjectOwner, children: children, dropSemanticsOfPreviousSiblings: dropSemanticsOfPreviousSiblings) {
+  }) : assert(children != null),
-    assert(children != null);
+       assert(children.length > 1),
-    assert(children.length > 1);
+       super(
-  }
+         renderObjectOwner: renderObjectOwner,
+         children: children,
+         dropSemanticsOfPreviousSiblings: dropSemanticsOfPreviousSiblings
+       );
 
   @override
   Iterable<SemanticsNode> compile({
@@ -946,8 +948,8 @@ class _ForkingSemanticsFragment extends _SemanticsFragment {
 /// [PipelineOwner] for the render tree from which you wish to read semantics.
 /// You can obtain the [PipelineOwner] using the [RenderObject.owner] property.
 class SemanticsHandle {
-  SemanticsHandle._(this._owner, this.listener) {
+  SemanticsHandle._(this._owner, this.listener)
-    assert(_owner != null);
+    : assert(_owner != null) {
     if (listener != null)
       _owner.semanticsOwner.addListener(listener);
   }

packages/flutter/lib/src/rendering/paragraph.dart

@@ -38,7 +38,12 @@ class RenderParagraph extends RenderBox {
     TextOverflow overflow: TextOverflow.clip,
     double textScaleFactor: 1.0,
     int maxLines,
-  }) : _softWrap = softWrap,
+  }) : assert(text != null),
+       assert(text.debugAssertIsValid()),
+       assert(softWrap != null),
+       assert(overflow != null),
+       assert(textScaleFactor != null),
+       _softWrap = softWrap,
        _overflow = overflow,
        _textPainter = new TextPainter(
          text: text,
@@ -46,13 +51,7 @@ class RenderParagraph extends RenderBox {
          textScaleFactor: textScaleFactor,
          maxLines: maxLines,
          ellipsis: overflow == TextOverflow.ellipsis ? _kEllipsis : null,
-       ) {
+       );
-    assert(text != null);
-    assert(text.debugAssertIsValid());
-    assert(softWrap != null);
-    assert(overflow != null);
-    assert(textScaleFactor != null);
-  }
 
   final TextPainter _textPainter;
 

packages/flutter/lib/src/rendering/performance_overlay.dart

@@ -66,15 +66,14 @@ class RenderPerformanceOverlay extends RenderBox {
     int rasterizerThreshold: 0,
     bool checkerboardRasterCacheImages: false,
     bool checkerboardOffscreenLayers: false,
-  }) : _optionsMask = optionsMask,
+  }) : assert(optionsMask != null),
-      _rasterizerThreshold = rasterizerThreshold,
+       assert(rasterizerThreshold != null),
-      _checkerboardRasterCacheImages = checkerboardRasterCacheImages,
+       assert(checkerboardRasterCacheImages != null),
-      _checkerboardOffscreenLayers = checkerboardOffscreenLayers {
+       assert(checkerboardOffscreenLayers != null),
-    assert(optionsMask != null);
+       _optionsMask = optionsMask,
-    assert(rasterizerThreshold != null);
+       _rasterizerThreshold = rasterizerThreshold,
-    assert(checkerboardRasterCacheImages != null);
+       _checkerboardRasterCacheImages = checkerboardRasterCacheImages,
-    assert(checkerboardOffscreenLayers != null);
+       _checkerboardOffscreenLayers = checkerboardOffscreenLayers;
-  }
 
   /// The mask is created by shifting 1 by the index of the specific
   /// [PerformanceOverlayOption] to enable.

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -201,10 +201,10 @@ class RenderConstrainedBox extends RenderProxyBox {
   RenderConstrainedBox({
     RenderBox child,
     @required BoxConstraints additionalConstraints,
-  }) : _additionalConstraints = additionalConstraints, super(child) {
+  }) : assert(additionalConstraints != null),
-    assert(additionalConstraints != null);
+       assert(additionalConstraints.debugAssertIsValid()),
-    assert(additionalConstraints.debugAssertIsValid());
+       _additionalConstraints = additionalConstraints,
-  }
+       super(child);
 
   /// Additional constraints to apply to [child] during layout
   BoxConstraints get additionalConstraints => _additionalConstraints;
@@ -311,10 +311,11 @@ class RenderLimitedBox extends RenderProxyBox {
     RenderBox child,
     double maxWidth: double.INFINITY,
     double maxHeight: double.INFINITY
-  }) : _maxWidth = maxWidth, _maxHeight = maxHeight, super(child) {
+  }) : assert(maxWidth != null && maxWidth >= 0.0),
-    assert(maxWidth != null && maxWidth >= 0.0);
+       assert(maxHeight != null && maxHeight >= 0.0),
-    assert(maxHeight != null && maxHeight >= 0.0);
+       _maxWidth = maxWidth,
-  }
+       _maxHeight = maxHeight,
+       super(child);
 
   /// The value to use for maxWidth if the incoming maxWidth constraint is infinite.
   double get maxWidth => _maxWidth;
@@ -400,11 +401,11 @@ class RenderAspectRatio extends RenderProxyBox {
   RenderAspectRatio({
     RenderBox child,
     @required double aspectRatio,
-  }) : _aspectRatio = aspectRatio, super(child) {
+  }) : assert(aspectRatio != null),
-    assert(aspectRatio != null);
+       assert(aspectRatio > 0.0),
-    assert(aspectRatio > 0.0);
+       assert(aspectRatio.isFinite),
-    assert(aspectRatio.isFinite);
+       _aspectRatio = aspectRatio,
-  }
+       super(child);
 
   /// The aspect ratio to attempt to use.
   ///
@@ -714,10 +715,11 @@ class RenderOpacity extends RenderProxyBox {
   ///
   /// The [opacity] argument must be between 0.0 and 1.0, inclusive.
   RenderOpacity({ double opacity: 1.0, RenderBox child })
-    : _opacity = opacity, _alpha = _getAlphaFromOpacity(opacity), super(child) {
+    : assert(opacity != null),
-    assert(opacity != null);
+      assert(opacity >= 0.0 && opacity <= 1.0),
-    assert(opacity >= 0.0 && opacity <= 1.0);
+      _opacity = opacity,
-  }
+      _alpha = _getAlphaFromOpacity(opacity),
+      super(child);
 
   @override
   bool get alwaysNeedsCompositing => child != null && (_alpha != 0 && _alpha != 255);
@@ -792,10 +794,11 @@ class RenderShaderMask extends RenderProxyBox {
     RenderBox child,
     @required ShaderCallback shaderCallback,
     BlendMode blendMode: BlendMode.modulate,
-  }) : _shaderCallback = shaderCallback, _blendMode = blendMode, super(child) {
+  }) : assert(shaderCallback != null),
-    assert(shaderCallback != null);
+       assert(blendMode != null),
-    assert(blendMode != null);
+       _shaderCallback = shaderCallback,
-  }
+       _blendMode = blendMode,
+       super(child);
 
   /// Called to creates the [Shader] that generates the mask.
   ///
@@ -849,9 +852,9 @@ class RenderBackdropFilter extends RenderProxyBox {
   ///
   /// The [filter] argument must not be null.
   RenderBackdropFilter({ RenderBox child, @required ui.ImageFilter filter })
-    : _filter = filter, super(child) {
+    : assert(filter != null),
-    assert(filter != null);
+      _filter = filter,
-  }
+      super(child);
 
   /// The image filter to apply to the existing painted content before painting
   /// the child.
@@ -1221,15 +1224,14 @@ class RenderPhysicalModel extends _RenderCustomClip<RRect> {
     BorderRadius borderRadius,
     double elevation: 0.0,
     @required Color color,
-  }) : _shape = shape,
+  }) : assert(shape != null),
+       assert(elevation != null),
+       assert(color != null),
+       _shape = shape,
        _borderRadius = borderRadius,
        _elevation = elevation,
        _color = color,
-       super(child: child) {
+       super(child: child);
-    assert(shape != null);
-    assert(elevation != null);
-    assert(color != null);
-  }
 
   /// The shape of the layer.
   ///
@@ -1347,14 +1349,13 @@ class RenderDecoratedBox extends RenderProxyBox {
     DecorationPosition position: DecorationPosition.background,
     ImageConfiguration configuration: ImageConfiguration.empty,
     RenderBox child
-  }) : _decoration = decoration,
+  }) : assert(decoration != null),
+       assert(position != null),
+       assert(configuration != null),
+       _decoration = decoration,
        _position = position,
        _configuration = configuration,
-       super(child) {
+       super(child);
-    assert(decoration != null);
-    assert(position != null);
-    assert(configuration != null);
-  }
 
   BoxPainter _painter;
 
@@ -1468,9 +1469,9 @@ class RenderTransform extends RenderProxyBox {
     FractionalOffset alignment,
     this.transformHitTests: true,
     RenderBox child
-  }) : super(child) {
+  }) : assert(transform != null),
-    assert(transform != null);
+       assert(alignment == null || (alignment.dx != null && alignment.dy != null)),
-    assert(alignment == null || (alignment.dx != null && alignment.dy != null));
+       super(child) {
     this.transform = transform;
     this.alignment = alignment;
     this.origin = origin;
@@ -1633,10 +1634,11 @@ class RenderFittedBox extends RenderProxyBox {
     RenderBox child,
     BoxFit fit: BoxFit.contain,
     FractionalOffset alignment: FractionalOffset.center
-  }) : _fit = fit, _alignment = alignment, super(child) {
+  }) : assert(fit != null),
-    assert(fit != null);
+       assert(alignment != null && alignment.dx != null && alignment.dy != null),
-    assert(alignment != null && alignment.dx != null && alignment.dy != null);
+       _fit = fit,
-  }
+       _alignment = alignment,
+       super(child);
 
   /// How to inscribe the child into the space allocated during layout.
   BoxFit get fit => _fit;
@@ -1771,9 +1773,9 @@ class RenderFractionalTranslation extends RenderProxyBox {
     FractionalOffset translation,
     this.transformHitTests: true,
     RenderBox child
-  }) : _translation = translation, super(child) {
+  }) : assert(translation == null || (translation.dx != null && translation.dy != null)),
-    assert(translation == null || (translation.dx != null && translation.dy != null));
+       _translation = translation,
-  }
+       super(child);
 
   /// The translation to apply to the child, as a multiple of the size.
   FractionalOffset get translation => _translation;
@@ -2020,12 +2022,11 @@ class RenderCustomPaint extends RenderProxyBox {
     CustomPainter foregroundPainter,
     Size preferredSize: Size.zero,
     RenderBox child,
-  }) : _painter = painter,
+  }) : assert(preferredSize != null),
+       _painter = painter,
        _foregroundPainter = foregroundPainter,
        _preferredSize = preferredSize,
-       super(child) {
+       super(child);
-    assert(preferredSize != null);
-  }
 
   /// The background custom paint delegate.
   ///
@@ -2490,9 +2491,9 @@ class RenderOffstage extends RenderProxyBox {
   RenderOffstage({
     bool offstage: true,
     RenderBox child
-  }) : _offstage = offstage, super(child) {
+  }) : assert(offstage != null),
-    assert(offstage != null);
+       _offstage = offstage,
-  }
+       super(child);
 
   /// Whether the child is hidden from the rest of the tree.
   ///
@@ -2609,9 +2610,8 @@ class RenderAbsorbPointer extends RenderProxyBox {
   RenderAbsorbPointer({
     RenderBox child,
     this.absorbing: true
-  }) : super(child) {
+  }) : assert(absorbing != null),
-    assert(absorbing != null);
+       super(child);
-  }
 
   /// Whether this render object absorbs pointers during hit testing.
   ///
@@ -2824,12 +2824,11 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     bool container: false,
     bool checked,
     String label
-  }) : _container = container,
+  }) : assert(container != null),
+       _container = container,
        _checked = checked,
        _label = label,
-       super(child) {
+       super(child);
-    assert(container != null);
-  }
 
   /// If 'container' is true, this RenderObject will introduce a new
   /// node in the semantics tree. Otherwise, the semantics will be

packages/flutter/lib/src/rendering/rotated_box.dart

@@ -26,8 +26,8 @@ class RenderRotatedBox extends RenderBox with RenderObjectWithChildMixin<RenderB
   RenderRotatedBox({
     @required int quarterTurns,
     RenderBox child
-  }) : _quarterTurns = quarterTurns {
+  }) : assert(quarterTurns != null),
-    assert(quarterTurns != null);
+       _quarterTurns = quarterTurns {
     this.child = child;
   }
 

packages/flutter/lib/src/rendering/shifted_box.dart

@@ -93,10 +93,10 @@ class RenderPadding extends RenderShiftedBox {
   RenderPadding({
     @required EdgeInsets padding,
     RenderBox child
-  }) : _padding = padding, super(child) {
+  }) : assert(padding != null),
-    assert(padding != null);
+       assert(padding.isNonNegative),
-    assert(padding.isNonNegative);
+       _padding = padding,
-  }
+       super(child);
 
   /// The amount to pad the child in each dimension.
   EdgeInsets get padding => _padding;
@@ -192,9 +192,9 @@ abstract class RenderAligningShiftedBox extends RenderShiftedBox {
   RenderAligningShiftedBox({
     FractionalOffset alignment: FractionalOffset.center,
     RenderBox child
-  }) : _alignment = alignment, super(child) {
+  }) : assert(alignment != null && alignment.dx != null && alignment.dy != null),
-    assert(alignment != null && alignment.dx != null && alignment.dy != null);
+       _alignment = alignment,
-  }
+       super(child);
 
   /// How to align the child.
   ///
@@ -259,12 +259,11 @@ class RenderPositionedBox extends RenderAligningShiftedBox {
     double widthFactor,
     double heightFactor,
     FractionalOffset alignment: FractionalOffset.center
-  }) : _widthFactor = widthFactor,
+  }) : assert(widthFactor == null || widthFactor >= 0.0),
+       assert(heightFactor == null || heightFactor >= 0.0),
+       _widthFactor = widthFactor,
        _heightFactor = heightFactor,
-       super(child: child, alignment: alignment) {
+       super(child: child, alignment: alignment);
-    assert(widthFactor == null || widthFactor >= 0.0);
-    assert(heightFactor == null || heightFactor >= 0.0);
-  }
 
   /// If non-null, sets its width to the child's width multipled by this factor.
   ///
@@ -499,10 +498,9 @@ class RenderSizedOverflowBox extends RenderAligningShiftedBox {
     RenderBox child,
     @required Size requestedSize,
     FractionalOffset alignment: FractionalOffset.center
-  }) : _requestedSize = requestedSize,
+  }) : assert(requestedSize != null),
-       super(child: child, alignment: alignment) {
+       _requestedSize = requestedSize,
-    assert(requestedSize != null);
+       super(child: child, alignment: alignment);
-  }
 
   /// The size this render box should attempt to be.
   Size get requestedSize => _requestedSize;
@@ -791,9 +789,9 @@ class RenderCustomSingleChildLayoutBox extends RenderShiftedBox {
   RenderCustomSingleChildLayoutBox({
     RenderBox child,
     @required SingleChildLayoutDelegate delegate
-  }) : _delegate = delegate, super(child) {
+  }) : assert(delegate != null),
-    assert(delegate != null);
+       _delegate = delegate,
-  }
+       super(child);
 
   /// A delegate that controls this object's layout.
   SingleChildLayoutDelegate get delegate => _delegate;
@@ -901,12 +899,11 @@ class RenderBaseline extends RenderShiftedBox {
     RenderBox child,
     @required double baseline,
     @required TextBaseline baselineType
-  }) : _baseline = baseline,
+  }) : assert(baseline != null),
+       assert(baselineType != null),
+       _baseline = baseline,
        _baselineType = baselineType,
-       super(child) {
+       super(child);
-    assert(baseline != null);
-    assert(baselineType != null);
-  }
 
   /// The number of logical pixels from the top of this box at which to position
   /// the child's baseline.

packages/flutter/lib/src/rendering/sliver_fill.dart

@@ -34,10 +34,10 @@ class RenderSliverFillViewport extends RenderSliverFixedExtentBoxAdaptor {
   RenderSliverFillViewport({
     @required RenderSliverBoxChildManager childManager,
     double viewportFraction: 1.0,
-  }) : _viewportFraction = viewportFraction, super(childManager: childManager) {
+  }) : assert(viewportFraction != null),
-    assert(viewportFraction != null);
+       assert(viewportFraction > 0.0),
-    assert(viewportFraction > 0.0);
+       _viewportFraction = viewportFraction,
-  }
+       super(childManager: childManager);
 
   @override
   double get itemExtent => constraints.viewportMainAxisExtent * viewportFraction;

packages/flutter/lib/src/rendering/sliver_grid.dart

@@ -456,10 +456,9 @@ class RenderSliverGrid extends RenderSliverMultiBoxAdaptor {
   RenderSliverGrid({
     @required RenderSliverBoxChildManager childManager,
     @required SliverGridDelegate gridDelegate,
-  }) : _gridDelegate = gridDelegate,
+  }) : assert(gridDelegate != null),
-       super(childManager: childManager) {
+       _gridDelegate = gridDelegate,
-    assert(gridDelegate != null);
+       super(childManager: childManager);
-  }
 
   @override
   void setupParentData(RenderObject child) {

packages/flutter/lib/src/rendering/sliver_multi_box_adaptor.dart

@@ -149,9 +149,8 @@ abstract class RenderSliverMultiBoxAdaptor extends RenderSliver
   /// The [childManager] argument must not be null.
   RenderSliverMultiBoxAdaptor({
     @required RenderSliverBoxChildManager childManager
-  }) : _childManager = childManager {
+  }) : assert(childManager != null),
-    assert(childManager != null);
+       _childManager = childManager;
-  }
 
   @override
   void setupParentData(RenderObject child) {

packages/flutter/lib/src/rendering/sliver_padding.dart

@@ -31,9 +31,9 @@ class RenderSliverPadding extends RenderSliver with RenderObjectWithChildMixin<R
   RenderSliverPadding({
     @required EdgeInsets padding,
     RenderSliver child,
-  }) : _padding = padding {
+  }) : assert(padding != null),
-    assert(padding != null);
+       assert(padding.isNonNegative),
-    assert(padding.isNonNegative);
+       _padding = padding {
     this.child = child;
   }
 

packages/flutter/lib/src/rendering/sliver_persistent_header.dart

@@ -270,11 +270,9 @@ class FloatingHeaderSnapConfiguration {
     @required this.vsync,
     this.curve: Curves.ease,
     this.duration: const Duration(milliseconds: 300),
-  }) {
+  }) : assert(vsync != null),
-    assert(vsync != null);
+       assert(curve != null),
-    assert(curve != null);
+       assert(duration != null);
-    assert(duration != null);
-  }
 
   /// The [TickerProvider] for the [AnimationController] that causes a
   /// floating header to snap in or out of view.

packages/flutter/lib/src/rendering/stack.dart

@@ -300,12 +300,12 @@ class RenderStack extends RenderBox
     FractionalOffset alignment: FractionalOffset.topLeft,
     StackFit fit: StackFit.loose,
     Overflow overflow: Overflow.clip
-  }) : _alignment = alignment,
+  }) : assert(alignment != null),
+       assert(fit != null),
+       assert(overflow != null),
+       _alignment = alignment,
        _fit = fit,
        _overflow = overflow {
-    assert(alignment != null);
-    assert(fit != null);
-    assert(overflow != null);
     addAll(children);
   }
 

packages/flutter/lib/src/rendering/table.dart

@@ -489,12 +489,11 @@ class RenderTable extends RenderBox {
     TableCellVerticalAlignment defaultVerticalAlignment: TableCellVerticalAlignment.top,
     TextBaseline textBaseline,
     List<List<RenderBox>> children
-  }) {
+  }) : assert(columns == null || columns >= 0),
-    assert(columns == null || columns >= 0);
+       assert(rows == null || rows >= 0),
-    assert(rows == null || rows >= 0);
+       assert(rows == null || children == null),
-    assert(rows == null || children == null);
+       assert(defaultColumnWidth != null),
-    assert(defaultColumnWidth != null);
+       assert(configuration != null) {
-    assert(configuration != null);
     _columns = columns ?? (children != null && children.isNotEmpty ? children.first.length : 0);
     _rows = rows ?? 0;
     _children = <RenderBox>[]..length = _columns * _rows;

packages/flutter/lib/src/rendering/viewport.dart

@@ -80,11 +80,10 @@ abstract class RenderViewportBase<ParentDataClass extends ContainerParentDataMix
   RenderViewportBase({
     AxisDirection axisDirection: AxisDirection.down,
     @required ViewportOffset offset,
-  }) : _axisDirection = axisDirection,
+  }) : assert(axisDirection != null),
-       _offset = offset {
+       assert(offset != null),
-    assert(axisDirection != null);
+       _axisDirection = axisDirection,
-    assert(offset != null);
+       _offset = offset;
-  }
 
   /// The direction in which the [SliverConstraints.scrollOffset] increases.
   ///
@@ -639,11 +638,11 @@ class RenderViewport extends RenderViewportBase<SliverPhysicalContainerParentDat
     double anchor: 0.0,
     List<RenderSliver> children,
     RenderSliver center,
-  }) : _anchor = anchor,
+  }) : assert(anchor != null),
+       assert(anchor >= 0.0 && anchor <= 1.0),
+       _anchor = anchor,
        _center = center,
        super(axisDirection: axisDirection, offset: offset) {
-    assert(anchor != null);
-    assert(anchor >= 0.0 && anchor <= 1.0);
     addAll(children);
     if (center == null && firstChild != null)
       _center = firstChild;

packages/flutter/lib/src/rendering/wrap.dart

@@ -91,18 +91,18 @@ class RenderWrap extends RenderBox with ContainerRenderObjectMixin<RenderBox, Wr
     WrapAlignment runAlignment: WrapAlignment.start,
     double runSpacing: 0.0,
     WrapCrossAlignment crossAxisAlignment: WrapCrossAlignment.start,
-  }) : _direction = direction,
+  }) : assert(direction != null),
+       assert(alignment != null),
+       assert(spacing != null),
+       assert(runAlignment != null),
+       assert(runSpacing != null),
+       assert(crossAxisAlignment != null),
+       _direction = direction,
        _alignment = alignment,
        _spacing = spacing,
        _runAlignment = runAlignment,
        _runSpacing = runSpacing,
        _crossAxisAlignment = crossAxisAlignment {
-    assert(direction != null);
-    assert(alignment != null);
-    assert(spacing != null);
-    assert(runAlignment != null);
-    assert(runSpacing != null);
-    assert(crossAxisAlignment != null);
     addAll(children);
   }