[Internals] setShadowDOMEnabled() shouldn't be used except a few tests.
https://bugs.webkit.org/show_bug.cgi?id=109642

Reviewed by Kent Tamura.

Source/WebCore:

InternalSettings.setShadowDOMEnabled() shouldn't be called after
any relevant DOM bindings are touched. However for fuzzers, it
isn't trivial to regulate its behavior.

This change whitelists the URL of running test for prevent
unintended API calls. This doesn't hurt the Internals usability
since the API is called from just a couple of tests and the number
isn't expected to grow.

Test: fast/dom/shadow/shadow-dom-enabled-flag-whitelist.html

* testing/InternalSettings.cpp:
(WebCore::urlIsWhitelisted):
(WebCore):
(WebCore::InternalSettings::setShadowDOMEnabled):

LayoutTests:

* fast/dom/shadow/shadow-dom-enabled-flag-whitelist-expected.txt: Added.
* fast/dom/shadow/shadow-dom-enabled-flag-whitelist.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@142726 268f45cc-cd09-0410-ab3c-d52691b4dbfc