13935 Refactor CanvasKit backend in preparation for platform views (cla: yes)

13950 Run benchmarks in Cirrus (cla: yes, waiting for tree to go green)

13951 Always set mEditable values when different in TextPlugin (cla: yes)

13952 Configures ICU to load the timezone data (cla: yes)

13965 Added API guards to flags in PlatformPlugin that were introduced after Flutter’s min SDK version. (cla: yes)

13976 Dynamically determine whether to use offscreen surface based on need (cla: yes)

13984 Listen to keyUp event on meta modified keys (cla: yes, platform-macos)

13985 [web] Initial support for LineMetrics (cla: yes, platform-web)