+++ This bug was initially created as a clone of Bug #105558 +++ After https://bugs.webkit.org/show_bug.cgi?id=105558#c3 , bug 105558 became INVALID. This bug then has a more limited scope of introducing a compositing trigger for scrollable frames, as a first step to add support for fast scrolling inner frames (similar to how overflow scrolling works).
Created attachment 180404 [details] patch
Comment on attachment 180404 [details] patch This seems fine. In chromium, we're currently only using this trigger when we're using force compositing mode, but that's just a policy choice and not something inherent to the code itself. Having it be a separate trigger seems perfectly reasonable.
Committed https://trac.webkit.org/changeset/139053