IDL compiler: sync Python to r167459

Python side to:
Oilpan: Move core/xml/ to oilpan's heap
https://codereview.chromium.org/166903010

BUG=239771
TBR=haraken
NOTRY=true

Review URL: https://codereview.chromium.org/176713003

git-svn-id: svn://svn.chromium.org/blink/trunk@167654 bbb929c8-8fbe-4397-9dbb-9b2b20218538