Merge 157914 "Prevent crash due to XMLDocumentParser destruction"

Merge 157914 "Prevent crash due to XMLDocumentParser destruction"

> Prevent crash due to XMLDocumentParser destruction
> 
> This patch prevents a crash in XMLDocumentParser::append due to the
> parser being destructed through doWrite. Destructing the parser can
> lead to the subsequent isStopped() check to fail to return, but by
> keeping the parser alive we ensure isStopped() correctly exits.
> 
> BUG=278908
> 
> Review URL: https://chromiumcodereview.appspot.com/23456031

TBR=pdr@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=158204

[kareng, 2013-09-23 20:35:16]

Committed patchset #1 manually as r158204.