ES2015 module issue with transpileOnly + decorators + interfaces

Hi there,

We have a very large Angular 2 codebase that we're attempting to move over to ts-loader; we're getting massive (4-5x) speed boosts compared to our existing awesome-typescript-loader setup, but sadly we're getting compilation issues when we turn on transpileOnly.

It only occurs when:

• Building ES2015 modules AND
• Using a class with a decorator on it AND
• The class uses an imported interface AND
• The imported interface comes from a module that also exports something concrete (e.g. a class or a const)

(webpack complains that it can't find the interface with a stack trace suggesting that it's processing harmony imports.)

I've created a repo with a standalone repro case in it: it's just tiny 2 files both of which are under 10 lines of code:

https://github.com/RoystonS/ts-loader-issue

(Is this related to what's discussed in issue #400?)

Thanks,
Royston.

Start with the standalone two-file reproduction at github.com/RoystonS/ts-loader-issue and run its webpack build with transpileOnly enabled. Reproduce the failure using ES2015 modules, a decorated class, and an imported interface from a module that also exports a concrete value; done means this combination compiles without the missing-interface or harmony-import error.