Remove CompositingChangeRepaint

CompositingChangeRepaintNow was always passed as the argument
for CompositingChangeRepaint so it can be safely removed.

Review URL: https://codereview.chromium.org/64953002

git-svn-id: svn://svn.chromium.org/blink/trunk@161575 bbb929c8-8fbe-4397-9dbb-9b2b20218538