Revert 159004 "Merge 158146 "[XHR] Abort method execution when m..."

Revert 159004 "Merge 158146 "[XHR] Abort method execution when m..."
This broke the 1599 branch.

> Merge 158146 "[XHR] Abort method execution when m_loader->cancel..."
> 
> > [XHR] Abort method execution when m_loader->cancel() in internalAbort() caused reentry
> > 
> > Calling cancel() on DocumentThreadableLoader may results in calling
> > window.onload synchronously. If open(), send(), etc. are called on the same
> > XMLHttpRequest object, it'll be hard to resolve conflict of states without
> > losing spec conformance. This CL avoids that by just aborting execution of
> > code for the outer method that calls internalAbort() if it returns false.
> > 
> > BUG=292422
> > 
> > Review URL: https://chromiumcodereview.appspot.com/24304004
> 
> TBR=tyoshino@chromium.org
> 
> Review URL: https://codereview.chromium.org/26209004

TBR=tyoshino@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=159087

[kerz_chromium, 2013-10-08 04:36:47]

Committed patchset #1 manually as r159087.