Stub NativeMenuItem
Merge pull request #1446 from mbebenita/nat

Stub NativeMenuItem
Fix check for `localStorage` support to not throw in Workers
Only try pushing the final tag in a SWF if the tag object exists
Merge pull request #1447 from tschneidereit/nat

SWF parser fixes
Merge branch 'nat' of github.com:mozilla/shumway into nat