RFR: 8353916: Unexpected event type for DOM mutation events with WebKit 620.1

[Kevin Rushforth]

On Tue, 8 Apr 2025 11:50:05 GMT, Jay Bhaskar <jbhaskar at openjdk.org> wrote:

> Issue: In WebKit 619.1, MutationEvent was properly handled and overridden, so casting to it worked as expected. In newer WebKit versions (like the one embedded in current JavaFX), MutationEvent is deprecated, and the actual event dispatched is just a generic DOM Event.
> Solution: restore the old style mutation event support, which will cause the returned events to again be instances of MutationEvent.

I confirm that this restores the logic that was present in 619.1 and inadvertently missing from 620.1.

All my testing looks good.

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Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1765#pullrequestreview-2751050495