Remove unused method setZoomWithoutReturnValue

When the third parameter to PropertyWrapper was removed in
https://codereview.chromium.org/139273007 (legacy animation engine
removal) setZoomWithoutReturnValue lost its last caller.

Review URL: https://codereview.chromium.org/324063002

git-svn-id: svn://svn.chromium.org/blink/trunk@176182 bbb929c8-8fbe-4397-9dbb-9b2b20218538