Merge 130313 - Crash when calling document.open during unload

Merge 130313 - Crash when calling document.open during unload
https://bugs.webkit.org/show_bug.cgi?id=98287

Reviewed by Nate Chapin.

Source/WebCore:

Calling document.open results in us nulling out m_documentLoader. This
code doesn't properly handle that case and crashes.

Test: fast/parser/document-open-in-unload.html

* loader/FrameLoader.cpp:
(WebCore::FrameLoader::commitProvisionalLoad):

LayoutTests:

Test that we don't crash when calling document.open during the unload event.

* fast/parser/document-open-in-unload-expected.txt: Added.
* fast/parser/document-open-in-unload.html: Added.


TBR=abarth@webkit.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=130514