Reviewed by ggaren.

        Fixes for our 3rd and 5th most common crashtracers:
        <rdar://problem/4233435> CrashTracer: 2698 crashes in Safari at com.apple.WebCore: khtml::RenderBlock::addChildToFlow + 156
        <rdar://problem/4129744> [REGRESSION]CrashTracer: ..400 crashes at com.apple.WebCore: DOM::NodeImpl::createRendererIfNeeded + 44

        Test case landed on trunk but not on branch.

        * khtml/xml/dom_docimpl.cpp:
        (DocumentImpl::setFocusNode): use m_inDetach bool copied from trunk
        * khtml/xml/dom_nodeimpl.cpp:
        (NodeImpl::NodeImpl):
        (NodeImpl::detach): set m_inDetach
        (NodeImpl::createRendererIfNeeded):
        (NodeBaseImpl::removeChildren): remove node from tree before calling detach.
        * khtml/xml/dom_nodeimpl.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@14054 268f45cc-cd09-0410-ab3c-d52691b4dbfc