Have DOMPatchSupport and DocumentFragment deal with Document references

Have DOMPatchSupport and DocumentFragment deal with Document references

Have DOMPatchSupport and DocumentFragment deal with Document references instead
of using pointers with assertions to make sure the pointers are non-null.

The DocumentFragment constructor still takes a Document pointer in argument
because of ShadowRoot which passes 0 as Document until it is set later on
by TreeScope. I need to investigate more to determine if the DocumentFragment
constructor can take a reference in.

BUG=281400
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=157237

[abarth-chromium, 2013-09-04 17:49:18]

lgtm

[commit-bot: I haz the power, 2013-09-04 18:29:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ch.dumez@sisa.samsung.com/23453033/1

[commit-bot: I haz the power, 2013-09-04 19:43:13]

Change committed as 157237

[do-not-use, 2013-09-04 20:05:58]

dglazkov@, if you have comments / idea about this part of my description, please
let me know:
"""
The DocumentFragment constructor still takes a Document pointer in argument
because of ShadowRoot which passes 0 as Document until it is set later on
by TreeScope. I need to investigate more to determine if the DocumentFragment
constructor can take a reference in.
"""

I haven't looked at it too much yet, but it is unfortunate that ShadowRoot seems
to be the only Node class passing 0 as document to its parent class Constructor.
This prevents us from using Document references in constructors from
DocumentFragment up to the Node class.

[dglazkov, 2013-09-04 20:22:01]

+morrita,hayato who probably know this code better than I do.