anchor.diff:  import "../../../Utils/async_utils.dart";
   import "pwd.dart";
   
  +bool isRedColor(String color) {
  +  String s = color.toLowerCase().replaceAll(" ", "");
  +  return s == "#f00" || s == "#ff0000" || s.startsWith("rgba(255,0,0");
  +}
  +
  +bool isGreenColor(String color) {
  +  String s = color.toLowerCase().replaceAll(" ", "");
  +  return s == "#0f0" || s == "#00ff00" || s.startsWith("rgba(0,255,0");
  +}
  +
   main() {
     document.body.setInnerHtml('''
         <canvas id="canvas">
  
positive.code:     ctx.fillStyle = "#f00";
      ctx.fillStyle = color;
      // Check that there is no red.
      if (new RegExp(r'^#(?!(FF0000|ff0000|f00)$)').hasMatch(ctx.fillStyle))
        testPassed("Setting color to " + color + " was successfully set.");
      else
        testFailed("Setting color to " + color + " was not set but should!");
  
negative.code:     ctx.fillStyle = "#0f0";
      ctx.fillStyle = color;
      // Check that the color is still green.
      if (isGreenColor(ctx.fillStyle))
        testPassed("Setting color to " + color + " was not set (as expected).");
      else
        testFailed("Setting color to " + color + " was successfully set but should not!");
  