Remove exports before calling closure compiler

[kristoferbaxter]

First take at resolving #56.

Having issues with npm linking locally, but this change removes all exports from source before Closure Compiler acts on the source. This prevents Closure Compiler from transpiling the export statements in some scenarios.

[kristoferbaxter]

@TrySound and @Andarist – This branch introduces tests for the scenario in #56.

Important note: If any code remains that is not part of the ECMASCRIPT5_STRICT subset, then Closure Compiler will attempt to transpile it, and insert the boilerplate you saw earlier.

[Andarist]

But if one targets newer subset they can just use the newer language_version without adding the boilerplate, right?

[kristoferbaxter]

If targeting a newer subset, you can omit the language_out value (the default is NO_TRANSPILE in this plugin), or can set the value to a newer version like ECMASCRIPT_2015. This would avoid boilerplate, yes.

Visit https://github.com/google/closure-compiler/wiki/Flags-and-Options for possible output options.