[Webkit-unassigned] [Bug 190884] New: requestAnimationFrame Stops Completing

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=190884

            Bug ID: 190884
           Summary: requestAnimationFrame Stops Completing
           Product: WebKit
           Version: Safari 12
          Hardware: Unspecified
                OS: macOS 10.14
            Status: NEW
          Severity: Major
          Priority: P2
         Component: HTML Events
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: daniel at danielscottjames.com

Created attachment 353045

  --> https://bugs.webkit.org/attachment.cgi?id=353045&action=review

Minimal Reproducible Example

The gist is that since Safari 12, it's possible to "break" requestAnimationFrame for every page in a grouped process. This makes our application practically unusable in  Safari.

I have attached a minimal reproducible example. I have verified that Safari 11 / Chrome / etc.. does not have this problem, and that this problem still occurs in the latest Safari Technology Preview (68)

Instructions:
Open index.html
Notice an incrementing counter.
Click the link to take you to loop.html
Notice the incrementing counter begins after some delay.
Without going back to the first page, close loop.html, taking you back to index.html

Expected:
The counters should continually increment while viewing the pages.

Actual:
Both: The counter in no longer incrementing. 
Safari 12: Other pages spawned by this page appear to get 0 or 1 completions to requestAnimationFrame and no more. (Additionally, interacting with the dev tools open in this state tends to crash the process, but I can't reproduce this reliably.)
Preview 68: Opening a new page tends to fix the counter. 


Example website:
Opening a document at www.lucidchart.com will put Safari 12 into this state.

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