Copy lib/dom tests that use dart:html to lib/html.

tests/dom/canvas_using_html_test.dart

-#library('CanvasUsingHtmlTest');
-#import('../../lib/unittest/unittest.dart');
-#import('../../lib/unittest/html_config.dart');
-#import('dart:html', prefix: 'html');
-#import('dart:html');
-
-// Version of Canvas test that implicitly uses dart:html library via unittests.
-
-main() {
-  CanvasElement canvas;
-  CanvasRenderingContext2D context;
-
-  canvas = new Element.tag('canvas');
-  canvas.attributes['width'] = 100;
-  canvas.attributes['height'] = 100;
-  document.body.nodes.add(canvas);
-  context = canvas.getContext('2d');
-
-  useHtmlConfiguration();
-  test('FillStyle', () {
-    context.fillStyle = "red";
-    context.fillRect(10, 10, 20, 20);
-
-    // TODO(vsm): Verify the result once we have the ability to read pixels.
-  });
-  test('SetFillColor', () {
-    // With floats.
-    context.setFillColor(10, 10, 10, 10);
-    context.fillRect(10, 10, 20, 20);
-
-    // With rationals.
-    context.setFillColor(10.0, 10.0, 10.0, 10.0);
-    context.fillRect(20, 20, 30, 30);
-
-    // With ints.
-    context.setFillColor(10, 10, 10, 10);
-    context.fillRect(30, 30, 40, 40);
-
-    // TODO(vsm): Verify the result once we have the ability to read pixels.
-  });
-  test('StrokeStyle', () {
-    context.strokeStyle = "blue";
-    context.strokeRect(30, 30, 10, 20);
-
-    // TODO(vsm): Verify the result once we have the ability to read pixels.
-  });
-  test('CreateImageData', () {
-    ImageData image = context.createImageData(canvas.width,
-                                              canvas.height);
-    Uint8ClampedArray bytes = image.data;
-
-    // FIXME: uncomment when numeric index getters are supported.
-    //var byte = bytes[0];
-
-    Expect.equals(40000, bytes.length);
-  });
-}