need @DocsEditable for Window, Element, Document, and CanvasRenderingContext

[DartBot]

This issue was originally filed by [email protected]

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Please add the @­DocsEditable annotation to the dart:html classes

Window
Element
Document
CanvasRenderingContext

So that we can add doc comments for those classes.

Thanks.
mem

[kwalrath]

Removed Area-Documentation label.
Added Area-HTML label.

[blois]

Fixed with https://codereview.chromium.org//23591046

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Added Fixed label.

[kwalrath]

Marked this as blocking #6098.

[blois]

But it's been fixed?

Also- we should be able to add the docs to the code itself in these cases (which is actually the preferred method when possible).