Node::lazyAttach should not set childNeedsStyleRecalc on non-ContainerNodes

When I changed Node::lazyAttach I made it setChildNeedsStyleRecalc() on every
node but this meant that we set the bit on Text nodes which have no children
and would never clear the bit. This doesn't really matter since nothing ever
looks at the child bit for Text, it does mean part of the tree was confused
so this patch corrects it so debugging tools make a bit more sense and so
we can ASSERT that no node in the tree ever has those bits after style recalc.

Review URL: https://chromiumcodereview.appspot.com/22825013

git-svn-id: svn://svn.chromium.org/blink/trunk@156263 bbb929c8-8fbe-4397-9dbb-9b2b20218538