Fixing dart:html links _not_ found in docs.json

tools/dom/src/CanvasImageSource.dart

Index: tools/dom/src/CanvasImageSource.dart
diff --git a/tools/dom/src/CanvasImageSource.dart b/tools/dom/src/CanvasImageSource.dart
index e0305335a851b7b56e3baa1be2b866bedf3793a9..ffcd34a417b5f08b33f4033b188b9d15f06d49a5 100644
--- a/tools/dom/src/CanvasImageSource.dart
+++ b/tools/dom/src/CanvasImageSource.dart
@@ -33,11 +33,10 @@ part of html;
  *
  * ## Other resources
  *
- * * [Image sources for 2D rendering contexts]
- * (http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#image-sources-for-2d-rendering-contexts)
- * from WHATWG.
- * * [Drawing images]
- * (http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-drawimage)
- * from WHATWG.
+ * * [Image sources for 2D rendering
+ *   contexts](https://html.spec.whatwg.org/multipage/scripting.html#image-sources-for-2d-rendering-contexts)
+ *   from WHATWG.
+ * * [Drawing images](https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-drawimage)
+ *   from WHATWG.
  */
 abstract class CanvasImageSource {}