Roll engine to 55b423f07ff747c2303c957fe151487b45585192.

55b423f07 Ensure assistiveTechnologyEnabled is initialized when the android view is set up (#5793)
3054f3183 Add touch events to the platform views method channel API. (#5796)
91c16af0c Revert "Roll Dart to 937ee2e8ca4b76499e24cd463f07bfb736bccd74. (#5745)" (#5799)
1a66f895b Roll Dart to 937ee2e8ca4b76499e24cd463f07bfb736bccd74. (#5745)
8d046a727 Revert "Roll src/third_party/skia 9e0d7e4072e4..8f8bf8880d9d (32 commits) (#5794)" (#5797)
e8d172cf3 Revert "Fix Dart 2 reload when running from a snapshot instead of platform.dill. (#5792)" (#5795)
624cf7e25 Fix Dart 2 reload when running from a snapshot instead of platform.dill. (#5792)
16da4710d Roll src/third_party/skia 9e0d7e4072e4..8f8bf8880d9d (32 commits) (#5794)
3fe63fd5d Add presubmit check for engine to flutter roll (#5790)

bin/internal/engine.version

-5557e3006e8346b2d3cccf3fa68859a00947641f
+55b423f07ff747c2303c957fe151487b45585192