Fix paths issue with modules in 'node_modules'.

Fixes #224, fixes #234.

BUG=https://github.com/google/traceur-compiler/issues/224
TEST=None (blocked by issue #221)

Review URL: https://github.com/google/traceur-compiler/issues/234

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I tried to recreate the old commit format. (Though I did leave out the "Patch from ..." part) The 'fixes' parts are to see if the other issues auto-close upon this pull's merge with master.

https://github.com/blog/1386-closing-issues-via-commit-messages