Remove unneeded counters from ScopeContentDistribution.
https://bugs.webkit.org/show_bug.cgi?id=116028

Reviewed by Andreas Kling.

They don't do much.

* WebCore.exp.in:
* dom/ShadowRoot.cpp:
(WebCore::ShadowRoot::ShadowRoot):
* dom/ShadowRoot.h:
        
    No need for registration code anymore.

* html/shadow/ContentDistributor.cpp:
(WebCore::ScopeContentDistribution::ScopeContentDistribution):
        
    Default m_insertionPointListIsValid to true to avoid crawling when there are no InsertionPoints.

(WebCore::ScopeContentDistribution::ensureInsertionPointList):
(WebCore::ScopeContentDistribution::registerInsertionPoint):
(WebCore::ScopeContentDistribution::unregisterInsertionPoint):
* html/shadow/ContentDistributor.h:
        
    Remove distributeNodeChildrenTo, it was only used by the older/younger shadow root code.

* testing/Internals.cpp:
* testing/Internals.h:
* testing/Internals.idl:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150010 268f45cc-cd09-0410-ab3c-d52691b4dbfc