Fix an optimisation in ContainerNode::notifyNodeInsertedInternal

R=tkent@chromium.org
BUG=544020

Review URL: https://codereview.chromium.org/1420653003

Cr-Commit-Position: refs/heads/master@{#355240}
void ContainerNode::removeDetachedChildren()
{
    ASSERT(!connectedSubframeCount());
    ASSERT(needsAttach());
    removeDetachedChildrenInContainer(*this);
}

void ContainerNode::removeDetachedChildren()
{
    ASSERT(!connectedSubframeCount());
    ASSERT(needsAttach());
    removeDetachedChildrenInContainer(*this);
}
