Trivial nit fixes (#12285)

packages/flutter/lib/src/foundation/diagnostics.dart

@@ -1386,7 +1386,7 @@ class IterableProperty<T> extends DiagnosticsProperty<Iterable<T>> {
   /// Create a diagnostics property for iterables (e.g. lists).
   ///
   /// The [ifEmpty] argument is used to indicate how an iterable [value] with 0
-  /// elements is displayed. If [ifEmpty] equals `null` that indicates that an
+  /// elements is displayed. If [ifEmpty] equals null that indicates that an
   /// empty iterable [value] is not interesting to display similar to how
   /// [defaultValue] is used to indicate that a specific concrete value is not
   /// interesting to display.
@@ -1433,10 +1433,10 @@ class IterableProperty<T> extends DiagnosticsProperty<Iterable<T>> {
   /// Priority level of the diagnostic used to control which diagnostics should
   /// be shown and filtered.
   ///
-  /// If [ifEmpty] is `null` and the [value] is an empty [Iterable] then level
+  /// If [ifEmpty] is null and the [value] is an empty [Iterable] then level
   /// [DiagnosticLevel.fine] is returned in a similar way to how an
-  /// [ObjectFlagProperty] handles when [ifNull] is `null` and the [value] is
+  /// [ObjectFlagProperty] handles when [ifNull] is null and the [value] is
-  /// `null`.
+  /// null.
   @override
   DiagnosticLevel get level {
     if (ifEmpty == null && value != null && value.isEmpty && super.level != DiagnosticLevel.hidden)
@@ -1605,8 +1605,8 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
   ///
   /// The [level] argument is just a suggestion and can be overridden if
   /// something else about the property causes it to have a lower or higher
-  /// level. For example, if the property value is `null` and [missingIfNull] is
+  /// level. For example, if the property value is null and [missingIfNull] is
-  /// `true`, [level] is raised to [DiagnosticLevel.warning].
+  /// true, [level] is raised to [DiagnosticLevel.warning].
   DiagnosticsProperty(
     String name,
     T value, {
@@ -2056,7 +2056,7 @@ abstract class Diagnosticable {
   /// Returns a debug representation of the object that is used by debugging
   /// tools and by [toStringDeep].
   ///
-  /// Leave [name] as `null` if there is not a meaningful description of the
+  /// Leave [name] as null if there is not a meaningful description of the
   /// relationship between the this node and its parent.
   ///
   /// Typically the [style] argument is only specified to indicate an atypical

packages/flutter/lib/src/material/expansion_tile.dart

@@ -54,7 +54,7 @@ class ExpansionTile extends StatefulWidget {
   /// Called when the tile expands or collapses.
   ///
   /// When the tile starts expanding, this function is called with the value
-  /// `true`. When the tile starts collapsing, this function is called with
+  /// true. When the tile starts collapsing, this function is called with
   /// the value false.
   final ValueChanged<bool> onExpansionChanged;
 

packages/flutter/lib/src/material/ink_well.dart

@@ -71,7 +71,7 @@ import 'theme.dart';
 /// ```dart
 /// assert(debugCheckHasMaterial(context));
 /// ```
-/// The parameter [enableFeedback] must not be `null`.
+/// The parameter [enableFeedback] must not be null.
 ///
 /// See also:
 ///

packages/flutter/lib/src/material/material_localizations.dart

@@ -102,7 +102,7 @@ abstract class MaterialLocalizations {
   /// This text theme is incomplete. For example, it lacks text color
   /// information. This theme must be merged with another text theme that
   /// provides the missing values. The text styles provided by this theme have
-  /// their [TextStyle.inherit] property set to `true`.
+  /// their [TextStyle.inherit] property set to true.
   ///
   /// Typically a complete theme is obtained via [Theme.of], which can be
   /// localized using the [Localizations] widget.

packages/flutter/lib/src/material/tabs.dart

@@ -303,7 +303,7 @@ class _IndicatorPainter extends CustomPainter {
 
   static bool _tabOffsetsNotEqual(List<double> a, List<double> b) {
     assert(a != null && b != null && a.length == b.length);
-    for(int i = 0; i < a.length; i++) {
+    for (int i = 0; i < a.length; i += 1) {
       if (a[i] != b[i])
         return true;
     }

packages/flutter/lib/src/material/theme_data.dart

@@ -457,7 +457,7 @@ class ThemeData {
   /// provided by the [localTextGeometry].
   ///
   /// The [TextStyle.inherit] field in the text styles provided by
-  /// [localTextGeometry] must be set to `true`.
+  /// [localTextGeometry] must be set to true.
   static ThemeData localize(ThemeData baseTheme, TextTheme localTextGeometry) {
     assert(baseTheme != null);
     assert(localTextGeometry != null);

packages/flutter/lib/src/material/time_picker.dart

@@ -287,7 +287,7 @@ class _MinuteControl extends StatelessWidget {
 /// Provides time picker header layout configuration for the given
 /// [timeOfDayFormat] passing [context] to each widget in the configuration.
 ///
-/// [timeOfDayFormat] and [context] must not be `null`.
+/// The [timeOfDayFormat] and [context] arguments must not be null.
 _TimePickerHeaderFormat _buildHeaderFormat(TimeOfDayFormat timeOfDayFormat, _TimePickerFragmentContext context) {
   // Creates an hour fragment.
   _TimePickerHeaderFragment hour(HourFormat hourFormat) {

packages/flutter/lib/src/material/two_level_list.dart

@@ -130,7 +130,7 @@ class TwoLevelSublist extends StatefulWidget {
   /// Called when the sublist expands or collapses.
   ///
   /// When the sublist starts expanding, this function is called with the value
-  /// `true`. When the sublist starts collapsing, this function is called with
+  /// true. When the sublist starts collapsing, this function is called with
   /// the value false.
   final ValueChanged<bool> onOpenChanged;
 

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

@@ -778,7 +778,7 @@ class _RootSemanticsFragment extends _InterestingSemanticsFragment {
   }
 }
 
-/// Represents a RenderObject that has [isSemanticBoundary] set to `true`.
+/// Represents a RenderObject that has [isSemanticBoundary] set to true.
 ///
 /// It returns the SemanticsNode for that [RenderObject].
 class _ConcreteSemanticsFragment extends _InterestingSemanticsFragment {
@@ -818,7 +818,7 @@ class _ConcreteSemanticsFragment extends _InterestingSemanticsFragment {
 }
 
 /// Represents a RenderObject that does not have [isSemanticBoundary] set to
-/// `true`, but which does have some semantic annotators.
+/// true, but which does have some semantic annotators.
 ///
 /// When it is compiled, if the nearest ancestor [_SemanticsFragment] that isn't
 /// also an [_ImplicitSemanticsFragment] is a [_RootSemanticsFragment] or a
@@ -2500,7 +2500,7 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
   /// Whether this [RenderObject] makes other [RenderObject]s previously painted
   /// within the same semantic boundary unreachable for accessibility purposes.
   ///
-  /// If `true` is returned, the [SemanticsNode]s for all siblings and cousins
+  /// If true is returned, the [SemanticsNode]s for all siblings and cousins
   /// of this node, that are earlier in a depth-first pre-order traversal, are
   /// dropped from the semantics tree up until a semantic boundary (as defined
   /// by [isSemanticBoundary]) is reached.
@@ -2562,9 +2562,9 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
   ///
   /// The parameters [onlyLocalUpdates] and [noGeometry] tell the framework
   /// how much of the semantics have changed. Bigger changes (indicated by
-  /// setting one or both parameters to `false`) are more expansive to compute.
+  /// setting one or both parameters to false) are more expansive to compute.
   ///
-  /// [onlyLocalUpdates] should be set to `true` to reduce cost if the semantics
+  /// [onlyLocalUpdates] should be set to true to reduce cost if the semantics
   /// update does not in any way change the shape of the semantics tree (e.g.
   /// [SemanticsNode]s will neither be added/removed from the tree nor be moved
   /// within the tree). In other words, with [onlyLocalChanges] the
@@ -2572,14 +2572,14 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
   /// local [SemanticsNode] (e.g. changing a label or flag) without affecting
   /// other nodes in the tree.
   ///
-  /// [onlyLocalUpdates] has to be set to `false` in the following cases as they
+  /// [onlyLocalUpdates] has to be set to false in the following cases as they
   /// will change the shape of the tree:
   ///
   /// 1. [isSemanticBoundary] changed its value.
-  /// 2. [semanticsAnnotator] changed from or to returning `null` and
+  /// 2. [semanticsAnnotator] changed from or to returning null and
-  ///    [isSemanticBoundary] isn't `true`.
+  ///    [isSemanticBoundary] isn't true.
   ///
-  /// [noGeometry] should be set to `true` to reduce cost if the geometry (e.g.
+  /// [noGeometry] should be set to true to reduce cost if the geometry (e.g.
   /// size and position) of the corresponding [SemanticsNode] has not
   /// changed. Examples for such semantic updates that don't require a geometry
   /// update are changes to flags, labels, or actions.
@@ -2766,7 +2766,7 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
   /// [markNeedsSemanticsUpdate] must not have `onlyLocalUpdates` set, as it is
   /// possible that the node should be entirely removed.
   ///
-  /// If the annotation should only happen under certain conditions, `null`
+  /// If the annotation should only happen under certain conditions, null
   /// should be returned if those conditions are currently not met to avoid
   /// the creation of an empty [SemanticsNode].
   SemanticsAnnotator get semanticsAnnotator => null;

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

@@ -209,7 +209,7 @@ abstract class RenderSliverPersistentHeader extends RenderSliver with RenderObje
   /// be excluded from the semantic scrolling area.
   ///
   /// [RenderSliver]s that stay on the screen even though the user has scrolled
-  /// past them (e.g. a pinned app bar) should set this to `true`.
+  /// past them (e.g. a pinned app bar) should set this to true.
   @protected
   bool get excludeFromSemanticsScrolling => _excludeFromSemanticsScrolling;
   bool _excludeFromSemanticsScrolling = false;

packages/flutter/lib/src/widgets/gesture_detector.dart

@@ -567,7 +567,7 @@ class RawGestureDetectorState extends State<RawGestureDetector> {
   /// The event can be interpreted by assistive technologies to provide
   /// additional feedback to the user about the state of the UI.
   ///
-  /// The event will not be sent if [excludeFromSemantics] is set to `true`.
+  /// The event will not be sent if [excludeFromSemantics] is set to true.
   void sendSemanticsEvent(SemanticsEvent event) {
     if (!widget.excludeFromSemantics) {
       final RenderSemanticsGestureHandler semanticsGestureHandler = context.findRenderObject();

packages/flutter/lib/src/widgets/localizations.dart

@@ -411,7 +411,7 @@ class Localizations extends StatefulWidget {
   /// Returns the localized resources object of the given `type` for the widget
   /// tree that corresponds to the given `context`.
   ///
-  /// Returns `null` if no resources object of the given `type` exists within
+  /// Returns null if no resources object of the given `type` exists within
   /// the given `context`.
   ///
   /// This method is typically used by a static factory method on the `type`

packages/flutter/test/material/switch_test.dart

@@ -169,7 +169,8 @@ void main() {
         ..circle(color: const Color(0x33000000))
         ..circle(color: const Color(0x24000000))
         ..circle(color: const Color(0x1f000000))
-          ..circle(color: Colors.yellow[500]));
+        ..circle(color: Colors.yellow[500])
+    );
     await tester.drag(find.byType(Switch), const Offset(-30.0, 0.0));
     await tester.pump();
 
@@ -183,6 +184,7 @@ void main() {
         ..circle(color: const Color(0x33000000))
         ..circle(color: const Color(0x24000000))
         ..circle(color: const Color(0x1f000000))
-          ..circle(color: Colors.red[500]));
+        ..circle(color: Colors.red[500])
+    );
   });
 }

packages/flutter_driver/lib/src/driver.dart

@@ -425,7 +425,7 @@ class FlutterDriver {
 
   /// Turns semantics on or off in the Flutter app under test.
   ///
-  /// Returns `true` when the call actually changed the state from on to off or
+  /// Returns true when the call actually changed the state from on to off or
   /// vice versa.
   Future<bool> setSemantics(bool enabled, { Duration timeout: _kShortTimeout }) async {
     final SetSemanticsResult result = SetSemanticsResult.fromJson(await _sendCommand(new SetSemantics(enabled, timeout: timeout)));

packages/flutter_test/lib/src/matchers.dart

@@ -434,10 +434,10 @@ class _EqualsIgnoringHashCodes extends Matcher {
   }
 }
 
-/// Returns `true` if [c] represents a whitespace code unit.
+/// Returns true if [c] represents a whitespace code unit.
 bool _isWhitespace(int c) => (c <= 0x000D && c >= 0x0009) || c == 0x0020;
 
-/// Returns `true` if [c] represents a vertical line unicode line art code unit.
+/// Returns true if [c] represents a vertical line unicode line art code unit.
 ///
 /// See [https://en.wikipedia.org/wiki/Box-drawing_character]. This method only
 /// specifies vertical line art code units currently used by Flutter line art.

packages/flutter_tools/lib/src/base/terminal.dart

@@ -118,11 +118,7 @@ class AnsiTerminal {
     }
     String choice;
     singleCharMode = true;
-    while(
+    while (isEmpty(choice) || choice.length != 1 || !acceptedCharacters.contains(choice)) {
-      isEmpty(choice)
-      || choice.length != 1
-      || !acceptedCharacters.contains(choice)
-     ) {
       if (isNotEmpty(prompt)) {
         printStatus(prompt, emphasis: true, newline: false);
         if (displayAcceptedCharacters)

packages/flutter_tools/lib/src/commands/analyze_base.dart

@@ -53,8 +53,8 @@ abstract class AnalyzeBase {
   bool get isBenchmarking => argResults['benchmark'];
 }
 
-/// Return `true` if [fileList] contains a path that resides inside the Flutter repository.
+/// Return true if [fileList] contains a path that resides inside the Flutter repository.
-/// If [fileList] is empty, then return `true` if the current directory resides inside the Flutter repository.
+/// If [fileList] is empty, then return true if the current directory resides inside the Flutter repository.
 bool inRepo(List<String> fileList) {
   if (fileList == null || fileList.isEmpty)
     fileList = <String>[fs.path.current];

packages/flutter_tools/lib/src/compile.dart

@@ -109,7 +109,7 @@ class ResidentCompiler {
   /// Otherwise, [mainPath] is ignored, but [invalidatedFiles] is recompiled
   /// into new binary.
   /// Binary file name is returned if compilation was successful, otherwise
-  /// `null` is returned.
+  /// null is returned.
   Future<String> recompile(String mainPath, List<String> invalidatedFiles) async {
     stdoutHandler.reset();
 

packages/flutter_tools/lib/src/devfs.dart

@@ -30,7 +30,7 @@ DevFSConfig get devFSConfig => context[DevFSConfig];
 abstract class DevFSContent {
   bool _exists = true;
 
-  /// Return `true` if this is the first time this method is called
+  /// Return true if this is the first time this method is called
   /// or if the entry has been modified since this method was last called.
   bool get isModified;
 
@@ -125,7 +125,7 @@ class DevFSByteContent extends DevFSContent {
     _isModified = true;
   }
 
-  /// Return `true` only once so that the content is written to the device only once.
+  /// Return true only once so that the content is written to the device only once.
   @override
   bool get isModified {
     final bool modified = _isModified;

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -673,7 +673,7 @@ int compareIosVersions(String v1, String v2) {
     final int v2Fragment = v2Fragments[i];
     if (v1Fragment != v2Fragment)
       return v1Fragment.compareTo(v2Fragment);
-    i++;
+    i += 1;
   }
   return v1Fragments.length.compareTo(v2Fragments.length);
 }

packages/flutter_tools/lib/src/version.dart

@@ -395,7 +395,7 @@ class VersionCheckError implements Exception {
 
 /// Runs [command] and returns the standard output as a string.
 ///
-/// If [lenient] is `true` and the command fails, returns an empty string.
+/// If [lenient] is true and the command fails, returns an empty string.
 /// Otherwise, throws a [ToolExit] exception.
 String _runSync(List<String> command, {bool lenient: true}) {
   final ProcessResult results = processManager.runSync(command, workingDirectory: Cache.flutterRoot);