Make hasRareData check an ASSERT_WITH_SECURITY_IMPLICATION

Given that the next thing done after checking hasRareData() is to access
the rare data as if it existed, this check failing likely means either
a use-after-free or accessing the render tree as NodeRareData.

R=inferno@chromium.org

Review URL: https://chromiumcodereview.appspot.com/23451002

git-svn-id: svn://svn.chromium.org/blink/trunk@156726 bbb929c8-8fbe-4397-9dbb-9b2b20218538