Clean up ContentData
https://bugs.webkit.org/show_bug.cgi?id=122421

Reviewed by Andreas Kling.

Replace uses of OwnPtr with std::unique_ptr and get rid of the ContentData::create overloads.

* css/StyleResolver.cpp:
(WebCore::StyleResolver::applyProperty):
* rendering/style/ContentData.cpp:
(WebCore::ContentData::clone):
* rendering/style/ContentData.h:
(WebCore::ContentData::setNext):
* rendering/style/RenderStyle.cpp:
(WebCore::RenderStyle::appendContent):
(WebCore::RenderStyle::setContent):
* rendering/style/RenderStyle.h:
* rendering/style/StyleRareNonInheritedData.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@157005 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Avoid layout in window.scroll{Y,X} when at topmost/leftmost position.
<https://webkit.org/b/122423>

Reviewed by Antti Koivisto.

Add a fast path for these properties to skip synchronous layout when
we are just going to return 0 anyway.

* page/DOMWindow.cpp:
(WebCore::DOMWindow::scrollX):
(WebCore::DOMWindow::scrollY):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@157006 268f45cc-cd09-0410-ab3c-d52691b4dbfc
CTTE: FrameLoader::notifier() should return a reference.
<https://webkit.org/b/122424>

Reviewed by Anders Carlsson.

It was just returning the address of an inline member, so we should
use a reference instead. Also made the backpointer to Frame in
ResourceLoadNotifier a reference.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@157007 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Element ancestor iterator should have a first() for convenience.
<https://webkit.org/b/122425>

Reviewed by Antti Koivisto.

Added an easy way to get the first element ancestor of a certain type
and put it to use in a few places.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@157008 268f45cc-cd09-0410-ab3c-d52691b4dbfc