IDL compiler: sync Python to r163132

Python side to:
Decouple FileSystem and WebSQL callbacks from VoidCallback and it non-refcounted
https://codereview.chromium.org/103083002/

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

Review URL: https://codereview.chromium.org/103613002

git-svn-id: svn://svn.chromium.org/blink/trunk@163144 bbb929c8-8fbe-4397-9dbb-9b2b20218538