[Mac] Don't dispatch wheel events for PhaseMayBegin|Cancelled|Ended
Mac will dispatch wheel events with |PlatformWheelEventPhase|, e.g.
1. |PhaseMayBegin| -> |PhaseCancelled| for two finger touch and lift
2. |PhaseMayBegin| -> |PhaseBegan| -> |PhaseChanged|* -> |PhaseEnded| for two finger scroll
3. |PhaseNone| for real mouse wheel scroll
Other platforms don't have phase info and only have events similar to
|PhaseBegan| and |PhaseChanged|. This CL filters those extra events
and only dispatch |PhaseBegan| and |PhaseChanged| for platform interop.
Note that |PhaseBegan| usually has non-zero delta, so we want to keep them.
Interop:
Firefox and Safari doesn't fire events for these phases, so we will match them after CL.
BUG=553732
Review-Url: https://codereview.chromium.org/2049323002
Cr-Commit-Position: refs/heads/master@{#403719}
3 files changed
