Remove obsolete comment in ShadowRoot.h

Source/core/dom/shadow/ShadowRoot.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 31 matching lines @@
 class HTMLShadowElement;
 class InsertionPoint;
 class ShadowRootRareData;
 class StyleSheetList;
 
 class CORE_EXPORT ShadowRoot final : public DocumentFragment, public TreeScope, public DoublyLinkedListNode<ShadowRoot> {
     DEFINE_WRAPPERTYPEINFO();
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(ShadowRoot);
     friend class WTF::DoublyLinkedListNode<ShadowRoot>;
 public:
-    // FIXME: We will support multiple shadow subtrees, however current implementation does not work well

[hayato, 2015/06/04 07:25:07]

The spec dropped multiple shadow roots, however, Blink is still supporting
multiple shadow roots. Blink just deprecated it.
Instead of removing the comment, it looks it might be better to update the
comment.

[kochi, 2015/06/04 07:47:38]

What comment do you think is useful?

I think the problem this comment is about is what the GitHub issue#102
https://github.com/w3c/webcomponents/issues/102
covers, and the resolution is to throw exception where
createShadowRoot() cannot be done.

So there is something to do in implementation, but is it worth
referring to the GitHub issue here?

// TODO(hayato): throw exception on some elements which createShadowRoot()
// cannot work (e.g. <canvas>).
// See https://github.com/w3c/webcomponents/issues/102

or
// TODO(hayato): http://crbug.com/234020 make createShadowRoot() always work
// on all elements.

for longer-term solution (?).

WDYT?

[hayato, 2015/06/04 08:20:14]

Only part we have to remove is "We'll support multiple shadow subtrees", I
think. That's obsolete.

Other parts still have the status of the current implementation of multiple
shadow roots. We can't remove other comment for the reason which the description
of the CL says. We have to continue the support of multiple shadow roots for a
while.

-    // if a shadow root is dynamically created. So we prohibit multiple shadow subtrees
-    // in several elements for a while.
-    // See https://bugs.webkit.org/show_bug.cgi?id=77503 and related bugs.
     enum ShadowRootType {
         UserAgentShadowRoot = 0,
         OpenShadowRoot
     };
 
     static PassRefPtrWillBeRawPtr<ShadowRoot> create(Document& document, ShadowRootType type)
     {
         return adoptRefWillBeNoop(new ShadowRoot(document, type));
     }
 
@@ skipping 97 matching lines @@
     return adjustedFocusedElement();
 }
 
 DEFINE_NODE_TYPE_CASTS(ShadowRoot, isShadowRoot());
 DEFINE_TYPE_CASTS(ShadowRoot, TreeScope, treeScope, treeScope->rootNode().isShadowRoot(), treeScope.rootNode().isShadowRoot());
 DEFINE_TYPE_CASTS(TreeScope, ShadowRoot, shadowRoot, true, true);
 
 } // namespace blink
 
 #endif // ShadowRoot_h