19008 No GPURasterizer::Draw trace event when layer tree holder is empty (cla: yes, waiting for tree to go green)

19009 Roll Skia from 21bbfc6c2dfe to 30212b7941d6 (6 revisions) (cla: yes, waiting for tree to go green)

19010 Roll Dart SDK from f043f9e5f6ea to f0ea02bc51f8 (22 revisions) (cla: yes, waiting for tree to go green)

19011 Roll CanvasKit to 0.16.2. (cla: yes)

19012 Remove print added for local testing (cla: yes)