Sandbox flags do not support document.domain control

Sandbox flags do not support document.domain control
https://bugs.webkit.org/show_bug.cgi?id=175281
<rdar://problem/33778936>

Reviewed by Chris Dumez.

Source/WebCore:

Update the 'setDomain' logic to honor the sandbox properties as defined in the current
HTML5 specification. This brings us in line with how Chrome and other browsers have
worked for some time.

Test: fast/frames/sandboxed-iframe-domain.html

* dom/Document.cpp:
(WebCore::Document::setDomain): Add check for sandbox flag (with appropriate error message)
* dom/SecurityContext.h:

LayoutTests:

* fast/frames/resources/sandboxed-iframe-set-domain.html: Added.
* fast/frames/sandboxed-iframe-domain.html: Added.
* fast/frames/sandboxed-iframe-domain-expected.txt: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@220427 268f45cc-cd09-0410-ab3c-d52691b4dbfc