9813 Made Picture::toImage happen on the IO thread with no need for an onscreen surface. (cla: yes)

9815 Made the persistent cache’s directory a const pointer. (cla: yes)

9816 Only release the image data in the unit-test once Skia has accepted ownership of it. (cla: yes)

9817 Revert “Roll src/third_party/dart 24725a8559..28f95fcd24 (32 commits)” (cla: yes)

9818 Convert run_tests to python, allow running on Mac/Windows and allow filters for tests. (cla: yes)

9819 Allow for dynamic thread merging on IOS for embedded view mutations (cla: yes)

9823 Roll buildroot to support bitcode enabled builds for iOS (cla: yes)