8065 add signal to pointer kinds (cla: yes)

8066 Revert “add signal to pointer kinds” (cla: yes)

8071 Only build a full Dart SDK when building for the host system (cla: yes)

8072 Delay the vsync callback till the frame start time specified by embedder. (cla: yes)

8073 Update a11y word forward/back enum names (cla: yes)

8074 Add script to help generate PR messages (cla: yes, waiting for tree to go green)

8077 Mark const extern (cla: yes)

8078 only partial rule revert (cla: yes)

8079 Fix text.dart height docs (cla: yes)

8080 Only build full sdk on release to speed up bots (cla: yes)