ShadowRootList should have recalculation flag instead of ShadowRoot.

ShadowRootList should have recalculation flag instead of ShadowRoot.
https://bugs.webkit.org/show_bug.cgi?id=79071

Reviewed by Hajime Morita.

When light children or shadow children are changed, we currently re-construct a shadow subtree.
However, when supporting multiple shadow subtrees, all shadow subtrees should be re-constructed.
So ShadowRootList should have re-construction flag instead of ShadowRoot.

Also, re-construction methods in ShadowRoot should be moved to ShadowRootList.

No new tests, should be convered by existing tests.

* dom/Element.cpp:
(WebCore::Element::recalcStyle):
(WebCore::Element::childrenChanged):
* dom/NodeRenderingContext.cpp:
(WebCore::NodeRenderingContext::hostChildrenChanged):
* dom/ShadowRoot.cpp:
(WebCore::ShadowRoot::ShadowRoot):
(WebCore::ShadowRoot::list):
* dom/ShadowRoot.h:
(WebCore):
(ShadowRoot):
* dom/ShadowRootList.cpp:
(WebCore::ShadowRootList::ShadowRootList):
(WebCore::ShadowRootList::reattach):
(WebCore):
(WebCore::ShadowRootList::childNeedsStyleRecalc):
(WebCore::ShadowRootList::needsStyleRecalc):
(WebCore::ShadowRootList::recalcShadowTreeStyle):
(WebCore::ShadowRootList::needsReattachHostChildrenAndShadow):
(WebCore::ShadowRootList::hostChildrenChanged):
(WebCore::ShadowRootList::setNeedsReattachHostChildrenAndShadow):
(WebCore::ShadowRootList::reattachHostChildrenAndShadow):
* dom/ShadowRootList.h:
(WebCore):
(ShadowRootList):
(WebCore::ShadowRootList::clearNeedsReattachHostChildrenAndShadow):
* html/shadow/HTMLContentElement.cpp:
(WebCore::HTMLContentElement::attach):
(WebCore::HTMLContentElement::detach):
(WebCore::HTMLContentElement::parseAttribute):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108713 268f45cc-cd09-0410-ab3c-d52691b4dbfc