Crash at CSSDefaultStyleSheets::ensureDefaultStyleSheetsForElement reported by fuzzer
https://bugs.webkit.org/show_bug.cgi?id=112328

Reviewed by Dimitri Glazkov.

Source/WebCore:

ensureDefaultStyleSheets should check whether page() is null or not.

Test: fast/css/ensure-default-style-sheets-crash.xhtml

* css/CSSDefaultStyleSheets.cpp:
(WebCore::CSSDefaultStyleSheets::ensureDefaultStyleSheetsForElement):

LayoutTests:

* fast/css/ensure-default-style-sheets-crash-expected.txt: Added.
* fast/css/ensure-default-style-sheets-crash.xhtml: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145864 268f45cc-cd09-0410-ab3c-d52691b4dbfc