anchor.diff:    );
     return completer.future;
   }
  -
  -/// Web doesn't support [decodeImageFromPixels]. Instead, generate a 1bpp BMP
  -/// and just use [instantiateImageCodec].
  -// TODO(dnfield): Remove this when https://github.com/flutter/flutter/issues/49244
  -// is resolved.
  -Future<ui.Image> _webCreateTestImage({
  -  required int width,
  -  required int height,
  -}) async {
  -  // See https://en.wikipedia.org/wiki/BMP_file_format for format examples.
  -  final int bufferSize = 0x36 + (width * height);
  -  final ByteData bmpData = ByteData(bufferSize);
  -  // 'BM' header
  -  bmpData.setUint8(0x00, 0x42);
  -  bmpData.setUint8(0x01, 0x4D);
  -  // Size of data
  -  bmpData.setUint32(0x02, bufferSize, Endian.little);
  -  // Offset where pixel array begins
  -  bmpData.setUint32(0x0A, 0x36, Endian.little);
  -  // Bytes in DIB header
  -  bmpData.setUint32(0x0E, 0x28, Endian.little);
  -  // width
  -  bmpData.setUint32(0x12, width, Endian.little);
  -  // height
  -  bmpData.setUint32(0x16, height, Endian.little);
  -  // Color panes
  -  bmpData.setUint16(0x1A, 0x01, Endian.little);
  -  // bpp
  -  bmpData.setUint16(0x1C, 0x01, Endian.little);
  -  // no compression
  -  bmpData.setUint32(0x1E, 0x00, Endian.little);
  -  // raw bitmap data size
  -  bmpData.setUint32(0x22, width * height, Endian.little);
  -  // print DPI width
  -  bmpData.setUint32(0x26, width, Endian.little);
  -  // print DPI height
  -  bmpData.setUint32(0x2A, height, Endian.little);
  -  // colors in the palette
  -  bmpData.setUint32(0x2E, 0x00, Endian.little);
  -  // important colors
  -  bmpData.setUint32(0x32, 0x00, Endian.little);
  -  // rest of data is zeroed as black pixels.
  -
  -  final ui.Codec codec = await ui.instantiateImageCodec(
  -    bmpData.buffer.asUint8List(),
  -  );
  -  final ui.FrameInfo frameInfo = await codec.getNextFrame();
  -  return frameInfo.image;
  -}
  
positive.code: import 'dart:typed_data';
  import 'dart:ui' as ui;
  
  import 'package:flutter/foundation.dart';
  import 'package:flutter/painting.dart';
  
  import 'test_async_utils.dart';
  
negative.code: });
  
  Future<ui.Image> _createImage(int width, int height) async {
    final Completer<ui.Image> completer = Completer<ui.Image>();
    ui.decodeImageFromPixels(
      Uint8List.fromList(List<int>.filled(width * height * 4, 0, growable: false)),
  