Sync the IDL interfaces in core/frame/ with their many specs

Source/core/frame/ImageBitmap.idl

Index: Source/core/frame/ImageBitmap.idl
diff --git a/Source/core/frame/ImageBitmap.idl b/Source/core/frame/ImageBitmap.idl
index b211d6ec29befbca566cb9547e5f856063921e1c..5cb21c8d1cf325c5bd6ee870a6792e1673fd8d88 100644
--- a/Source/core/frame/ImageBitmap.idl
+++ b/Source/core/frame/ImageBitmap.idl
@@ -2,9 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// https://html.spec.whatwg.org/#images
+
 [
+    // TODO(philipj): Exposed=(Window,Worker)
     WillBeGarbageCollected,
 ] interface ImageBitmap {
+    // TODO(philipj): width/height should be unsigned long.
     readonly attribute long width;
     readonly attribute long height;
 };