IDL compiler: sync Python to r163026

Python side to:
Manage RequestAnimationFrameCallbacks with OwnPtrs instead of RefPtrs
https://codereview.chromium.org/92913002/

BUG=239771
BUG=323681
NOTRY=true
TBR=haraken

Review URL: https://codereview.chromium.org/100873002

git-svn-id: svn://svn.chromium.org/blink/trunk@163049 bbb929c8-8fbe-4397-9dbb-9b2b20218538