[web] Cleanup everything HTML from the framework (#162837)

Things being removed:

- Custom image filter logic in `cupertino/dialog.dart`.
- Network image support for the HTML renderer.
- Shader warm up guard for the HTML renderer.
- Custom caret metrics logic in `text_painter.dart`.

packages/flutter/lib/src/cupertino/dialog.dart

@@ -684,7 +684,7 @@ class CupertinoPopupSurface extends StatelessWidget {
       isVibrancePainted = debugIsVibrancePainted;
       return true;
     }());
-    if ((kIsWeb && !isSkiaWeb) || !isVibrancePainted) {
+    if (!isVibrancePainted) {
       if (blurSigma == 0) {
         return null;
       }

packages/flutter/lib/src/painting/_network_image_web.dart

@@ -5,7 +5,6 @@
 import 'dart:async';
 import 'dart:js_interop';
 import 'dart:ui' as ui;
-import 'dart:ui_web' as ui_web;
 
 import 'package:flutter/foundation.dart';
 
@@ -134,9 +133,6 @@ class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkIm
     return collector;
   }
 
-  // HTML renderer does not support decoding network images to a specified size. The decode parameter
-  // here is ignored and `ui_web.createImageCodecFromUrl` will be used directly
-  // in place of the typical `instantiateImageCodec` method.
   Future<ImageStreamCompleter> _loadAsync(
     NetworkImage key,
     _SimpleDecoderCallback decode,
@@ -176,9 +172,6 @@ class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkIm
     final bool containsNetworkImageHeaders = key.headers?.isNotEmpty ?? false;
     // When headers are set, the image can only be loaded by decoding.
     //
-    // For the HTML renderer, `ui_web.createImageCodecFromUrl` method is not
-    // capable of handling headers.
-    //
     // For CanvasKit and Skwasm, it is not possible to load an <img> element and
     // pass the headers with the request to fetch the image. Since the user has
     // provided headers, this function should assume the headers are required to
@@ -188,32 +181,6 @@ class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkIm
       return loadViaDecode();
     }
 
-    if (!isSkiaWeb) {
-      // This branch is only hit by the HTML renderer, which is deprecated. The
-      // HTML renderer supports loading images with CORS restrictions, so we
-      // don't need to catch errors and try loading the image in an <img> tag
-      // in this case.
-
-      // Resolve the Codec before passing it to
-      // [MultiFrameImageStreamCompleter] so any errors aren't reported
-      // twice (once from the MultiFrameImageStreamCompleter) and again
-      // from the wrapping [ForwardingImageStreamCompleter].
-      final Uri resolved = Uri.base.resolve(key.url);
-      final ui.Codec codec = await ui_web.createImageCodecFromUrl(
-        resolved,
-        chunkCallback: (int bytes, int total) {
-          chunkEvents.add(ImageChunkEvent(cumulativeBytesLoaded: bytes, expectedTotalBytes: total));
-        },
-      );
-      return MultiFrameImageStreamCompleter(
-        chunkEvents: chunkEvents.stream,
-        codec: Future<ui.Codec>.value(codec),
-        scale: key.scale,
-        debugLabel: key.url,
-        informationCollector: _imageStreamInformationCollector(key),
-      );
-    }
-
     switch (webHtmlElementStrategy) {
       case image_provider.WebHtmlElementStrategy.never:
         return loadViaDecode();

packages/flutter/lib/src/painting/shader_warm_up.dart

@@ -90,20 +90,17 @@ abstract class ShaderWarmUp {
     await warmUpOnCanvas(canvas);
     final ui.Picture picture = recorder.endRecording();
     assert(debugCaptureShaderWarmUpPicture(picture));
-    if (!kIsWeb || isSkiaWeb) {
-      // Picture.toImage is not implemented on the html renderer.
-      TimelineTask? debugShaderWarmUpTask;
+    TimelineTask? debugShaderWarmUpTask;
+    if (!kReleaseMode) {
+      debugShaderWarmUpTask = TimelineTask()..start('Warm-up shader');
+    }
+    try {
+      final ui.Image image = await picture.toImage(size.width.ceil(), size.height.ceil());
+      assert(debugCaptureShaderWarmUpImage(image));
+      image.dispose();
+    } finally {
       if (!kReleaseMode) {
-        debugShaderWarmUpTask = TimelineTask()..start('Warm-up shader');
-      }
-      try {
-        final ui.Image image = await picture.toImage(size.width.ceil(), size.height.ceil());
-        assert(debugCaptureShaderWarmUpImage(image));
-        image.dispose();
-      } finally {
-        if (!kReleaseMode) {
-          debugShaderWarmUpTask!.finish();
-        }
+        debugShaderWarmUpTask!.finish();
       }
     }
     picture.dispose();

packages/flutter/lib/src/painting/text_painter.dart

@@ -1528,9 +1528,7 @@ class TextPainter {
     final _TextPainterLayoutCacheWithOffset cachedLayout = _layoutCache!;
     // If nothing is laid out, top start is the only reasonable place to place
     // the cursor.
-    // The HTML renderer reports numberOfLines == 1 when the text is empty:
-    // https://github.com/flutter/flutter/issues/143331
-    if (cachedLayout.paragraph.numberOfLines < 1 || plainText.isEmpty) {
+    if (cachedLayout.paragraph.numberOfLines < 1) {
       // TODO(LongCatIsLooong): assert when an invalid position is given.
       return null;
     }
@@ -1588,31 +1586,16 @@ class TextPainter {
       boxHeightStyle: ui.BoxHeightStyle.strut,
     );
 
-    if (boxes.isNotEmpty) {
-      final bool anchorToLeft = switch (glyphInfo.writingDirection) {
-        TextDirection.ltr => anchorToLeadingEdge,
-        TextDirection.rtl => !anchorToLeadingEdge,
-      };
-      final TextBox box = anchorToLeft ? boxes.first : boxes.last;
-      metrics = _LineCaretMetrics(
-        offset: Offset(anchorToLeft ? box.left : box.right, box.top),
-        writingDirection: box.direction,
-        height: box.bottom - box.top,
-      );
-    } else {
-      // Fall back to glyphInfo. This should only happen when using the HTML renderer.
-      assert(kIsWeb && !isSkiaWeb);
-      final Rect graphemeBounds = glyphInfo.graphemeClusterLayoutBounds;
-      final double dx = switch (glyphInfo.writingDirection) {
-        TextDirection.ltr => anchorToLeadingEdge ? graphemeBounds.left : graphemeBounds.right,
-        TextDirection.rtl => anchorToLeadingEdge ? graphemeBounds.right : graphemeBounds.left,
-      };
-      metrics = _LineCaretMetrics(
-        offset: Offset(dx, graphemeBounds.top),
-        writingDirection: glyphInfo.writingDirection,
-        height: graphemeBounds.height,
-      );
-    }
+    final bool anchorToLeft = switch (glyphInfo.writingDirection) {
+      TextDirection.ltr => anchorToLeadingEdge,
+      TextDirection.rtl => !anchorToLeadingEdge,
+    };
+    final TextBox box = anchorToLeft ? boxes.first : boxes.last;
+    metrics = _LineCaretMetrics(
+      offset: Offset(anchorToLeft ? box.left : box.right, box.top),
+      writingDirection: box.direction,
+      height: box.bottom - box.top,
+    );
 
     cachedLayout._previousCaretPositionKey = caretPositionCacheKey;
     return _caretMetrics = metrics;