IDL compiler: sync Python to r166799

Python side to:
Remove [OverrideBuiltins] from HTMLCollection
https://codereview.chromium.org/158273002

BUG=239771
BUG=341192
BUG=341924
TBR=haraken
NOTRY=true

Review URL: https://codereview.chromium.org/144283009

git-svn-id: svn://svn.chromium.org/blink/trunk@166957 bbb929c8-8fbe-4397-9dbb-9b2b20218538