Fix #1408: packageJSDependencies is broken.
Merge pull request #1420 from sjrd/fix-package-js-deps

Fix #1408: packageJSDependencies is broken.
Fix #1421: Emit correct kind in ClassInfos
Don't remove originals when checking sizes
Don't reset nonExistent flag in Analyzer
Fix #1410: Cleanup ScalaJSOptimizer
Merge pull request #1422 from gzm0/linker

Cleanup Linker / Optimizer