Fix sourceMap bug

[nicolas-pantel]

source: omsmith/browserify-ngannotate#20

This bug is caused by the lack of file in applySourceMap parameters.

[ryepup]

I'm getting some test failures after updating my npm packages, and this patch fixes it.

27 06 2016 09:01:48.331:ERROR [karma]: Error: SourceMapGenerator.prototype.applySourceMap requires either an explicit source file, or the source map's "file" property. Both were omitted.
    at SourceMapGenerator_applySourceMap [as applySourceMap] (my-project\node_modules\source-map\lib\source-map-generator.js:177:15)
    at SourceMapper.applySourceMap (my-project\node_modules\ng-annotate\build\es5\generate-sourcemap.js:92:20)
    at generateSourcemap (my-project\node_modules\ng-annotate\build\es5\generate-sourcemap.js:115:20)
    at ngAnnotate (my-project\node_modules\ng-annotate\build\es5\ng-annotate-main.js:1221:9)
    at DestroyableTransform.flush [as _flush] (my-project\node_modules\browserify-ngannotate\index.js:45:24)
    at DestroyableTransform.<anonymous> (my-project\node_modules\through2\node_modules\readable-stream\lib\_stream_transform.js:115:49)
    at DestroyableTransform.g (events.js:286:16)
    at emitNone (events.js:86:13)
    at DestroyableTransform.emit (events.js:185:7)
    at prefinish (my-project\node_modules\through2\node_modules\readable-stream\lib\_stream_writable.js:465:12)
    at finishMaybe (my-project\node_modules\through2\node_modules\readable-stream\lib\_stream_writable.js:473:7)
    at endWritable (my-project\node_modules\through2\node_modules\readable-stream\lib\_stream_writable.js:485:3)
    at DestroyableTransform.Writable.end (my-project\node_modules\through2\node_modules\readable-stream\lib\_stream_writable.js:455:41)
    at DuplexWrapper.onend (my-project\node_modules\readable-stream\lib\_stream_readable.js:507:10)
    at DuplexWrapper.g (events.js:286:16)
    at emitNone (events.js:91:20)
npm ERR! Test failed.  See above for more details.

[olov]

#245