Replace static_cast<Element*> with toElement
Replace static_cast<Element*> with toElement

Turns out only Node had some left.

Review URL: https://chromiumcodereview.appspot.com/17094020

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@152866 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs