26133 Revert “SceneBuilder.addPicture returns the layer” (cla: yes, waiting for tree to go green, platform-web)

26134 Reland “Fix a11y placeholder on desktop; auto-enable engine semantics” (cla: yes, platform-web)

26135 Roll Dart SDK from c119194b23d9 to ba8506bdcef7 (2 revisions) (cla: yes, waiting for tree to go green)

26136 Roll Skia from ca9f6a855071 to 3193a04b09d8 (21 revisions) (cla: yes, waiting for tree to go green)

26137 Roll Fuchsia Mac SDK from mdsssGtoC… to y3xw-lhxW… (cla: yes, waiting for tree to go green)