66688 Dispose of images after using them (a: tests, cla: yes, framework, perf: memory, severe: performance)

66743 cleanup completed todo and unused variable for WidgetTester (a: tests, cla: yes, framework, waiting for tree to go green)

66745 move resampler to handlePointerEvent and fix complex_layout_android__scroll_smoothness with PointerEvent (a: tests, cla: yes, framework, team, waiting for tree to go green)

66849 Flutter 1.22.0-12.3.pre framework cherrypicks (a: tests, cla: yes, engine, f: cupertino, f: material design, framework, team, tool)

66916 Re-enables tests previously failing due to new semantics flag. (a: accessibility, a: tests, cla: yes, framework, waiting for tree to go green)