Remove extern/editing_typedefs.js
Merge pull request #1 from hajimehoshi-chromium/remove-editing-typedefs

Remove extern/editing_typedefs.js
[testing] Get rid of unused file "commands/undo_command_unittest.js".
Note: "undo" and "redo" commands are always checked for |testCaseFor(commandName, testFunction)|.
[checker] Make "checker.py" to take path to closure compiler jar file.
[checker] Continue checking JS source files after checking failure.
[commands] Fix JS type annotations.
[testing] Fix latency time unit to "ms".