* Stop using build_runner for dart2js
* fixes to yield when computing hashes and to imports
* add missing await
* Update filecache_test.dart
* Fix paths in filecache test
* use file uri for import
* add test cases and configurable override
* remove test dep
* fix filepaths for windows
* test no longer failing
* fix paths for test cases
* fix typo
* address comments
* make a constant
* make filehash async and use constant
* fix silly logic error
