25985 Add an allowlist flag for Skia trace event categories (cla: yes, waiting for tree to go green)

25988 Platform channels, eliminate objc copies (platform-ios, platform-android, cla: yes, waiting for tree to go green, platform-macos, platform-fuchsia, embedder)

25991 Make SceneBuilder.push* not return nullable objects (cla: yes, waiting for tree to go green, platform-web)

25999 Roll Dart SDK from b8f4018535fa to 86c749398b3a (16 revisions) (cla: yes, waiting for tree to go green)

26001 Roll Fuchsia Mac SDK from uQgs5ZmFq… to aCsEHpnS0… (cla: yes, waiting for tree to go green)