Chrome Version: 66.0.3359.0
OS: macOS 10.12.6

Initially reported by mehmet@: crbug.com/807683#c49

What steps will reproduce the problem?
(1) Run chrome with --site-per-process
(2) Visit chromium.org/developers/calendar
(3) Scroll down the page until the rubber-banding effect activates at the bottom of the page
(4) Scroll back up to the table of version numbers
(5) Attempt to scroll the inner iframe

What is the expected result?
The inner iframe should scroll.

What happens instead?
The inner iframe does not scroll. The scroll is bubbled instead.

Further information from 807683:
Device: iMac 21,5 (2012) Non-Retina and MagicMouse1
mehmet@ reported that it does not reproduce with --disable-threaded-scrolling, indicating an issue with the compositor thread.

Initial hypothesis from wjmaclean@:
"I suspect the rubber-banding issue occurs because, when the rubber-banding is invoked in the main-frame's renderer (and not in the OOPIF's renderer), there is at present no way for the OOPIF's ScrollingCoordinator to know to call UpdateAfterCompositingChangeIfNeeded ... although it may get called for other reasons, causing the NFSRs to get changed during rubber-banding but not again afterwards."