8635 Remove unnecessary DartIO::EntropySource wrapper (cla: yes)

8637 Generate layer unique id for raster cache key (cla: yes)

8638 Custom RTL handling for ghost runs, NotoNaskhArabic test font (cla: yes)

8640 Remove DartSnapshotBuffer and dry up snapshot resolution logic. (cla: yes)

8642 Remove unused Settings::ToString. (cla: yes)

8643 Allow specifying the Mac SDK path as an environment variable to //flutter/tools/gn (cla: yes)

8644 Revert “Remove DartSnapshotBuffer and dry up snapshot resolution logic.” (cla: yes)

8645 Reland “Remove DartSnapshotBuffer and dry up snapshot resolution logic”. (cla: yes)

8646 Disable auth codes for Observatory test (cla: yes)