Rework MutationObserver callback. #849
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Previously, MutationObserver callbacks where called using the `jsCallScopeEnd` mechanism. This was slow and resulted in records split in a way that callers might not expect. `jsCallScopeEnd` has been removed. The new approach uses the loop.timeout mechanism, much like a window.setTimeout and only registers a timeout when events have been handled. It should perform much better. Exactly how MutationRecords are supposed to be grouped is still a mystery to me. This new grouping is still wrong in many cases (according to WPT), but appears slightly less wrong; I'm pretty hopeful clients don't really have hard-coded expectations for this though. Also implement the attributeFilter option of MutationObserver. (Github)
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Previously, MutationObserver callbacks where called using the
jsCallScopeEndmechanism. This was slow and resulted in records split in a way that callers might not expect.jsCallScopeEndhas been removed.The new approach uses the loop.timeout mechanism, much like a window.setTimeout and only registers a timeout when events have been handled. It should perform much better.
Exactly how MutationRecords are supposed to be grouped is still a mystery to me. This new grouping is still wrong in many cases (according to WPT), but appears slightly less wrong; I'm pretty hopeful clients don't really have hard-coded expectations for this though.
Also implement the attributeFilter option of MutationObserver. (Github)