[XHR] Abort method execution when m_loader->cancel() in internalAbort() caused reentry

[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
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=158146

[tyoshino (SeeGerritForStatus), 2013-09-20 14:13:30]

As discussed at this old CL https://codereview.chromium.org/23465030/
made this new one which aborts outer method call instead of inner one.

Since outer send() call fails, expectation file for reentrant-cancel will
contain exception log.

[Nate Chapin, 2013-09-20 19:29:55]

Ideally in the long term, we'll make events not do crazy, reentrant things. But
until that day, LGTM.

[commit-bot: I haz the power, 2013-09-20 20:03:06]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tyoshino@chromium.org/24304004/1

[commit-bot: I haz the power, 2013-09-20 20:17:24]

Retried try job too often on blink_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=blink_pres...

[commit-bot: I haz the power, 2013-09-20 20:41:19]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tyoshino@chromium.org/24304004/1

[commit-bot: I haz the power, 2013-09-21 01:35:39]

Change committed as 158146