SourceMap info is broken if contains empty js file.

[vvakame]

SourceMap info is broken if contains empty js file.

reproduction code.
https://github.com/vvakame/karma-espower-preprocessor-typescript-sample/tree/sourcemap-broken
this code has a empty.ts. it is not contains any statement.

I think this is not espower's problems. but I can't specified which part is bad. sorry.

[twada]

Okay, I'll check it out.

[vvakame]

https://gist.github.com/vvakame/bd679c6ef75e319537ad
this is my note.

[twada]

@vvakame Thanks!