HashTraits<RefPtr<P> >::peek should consider empty value

HashTraits<RefPtr<P> >::peek() should consider passing of empty value which is
raw pointer equal to '0', and return it right away instead of converting it to RefPtr
and invoking get().

Review URL: https://chromiumcodereview.appspot.com/14998005

git-svn-id: svn://svn.chromium.org/blink/trunk@149988 bbb929c8-8fbe-4397-9dbb-9b2b20218538
1 file changed