6936 Return real null instead of null string when locale has not been set in locale closure. (cla: yes)

6945 Adds force cursor support (cla: yes)

6961 Add hover event support to the engine (cla: yes)

6967 Eliminate obsolete FlutterDartProject initializers (cla: yes)

6973 Eliminate main_dart_file_path, package_file_path (cla: yes)

6977 Rename dart-non-checked-mode: disable-dart-asserts (cla: yes)

6985 Fix keyboard not showing for targetSdk 28 (cla: yes)

6989 Japanese Clear Text Crash (cla: yes)

6991 MInor Docs to runtime controller WindowData (cla: yes)