Remove unused parameter to windowClipRectForFrameOwner

All callers pass |true| for this Boolean parameter

R=ojan@chromium.org
BUG=343769

Review URL: https://codereview.chromium.org/171163002

git-svn-id: svn://svn.chromium.org/blink/trunk@167381 bbb929c8-8fbe-4397-9dbb-9b2b20218538