TypeScript implement custom resolver

[guybedford]

To ensure that bundle dependencies are normalized correctly, it is necessary to have a custom resolver to pass into TypeScript.

@vladima you mentioned previously this was the plan for custom resolutions? Please keep me posted on how that goes.

[vladima]

@guybedford sure. Currently we plan to expose custom resolution via CompilerHost.resolveModuleName so host can implement any resolution policy it needs. Can you please tell if it will cover your scenarios?

[guybedford]

@vladima thanks yes that looks exactly right. In SystemJS we can always relate every module to an absolute URL or filepath, but it may be worth considering relaxing this constraint and allowing virtual naming as well. For example, we use the @empty module in SystemJS as an output for this for nulled out modules (an edge case certainly, but to illustrate).

[vladima]

@guybedford this PR on the TypeScript side should allow to pass map (originalName -> newName, effectively load.depMap) to transpiler. Can you please check if it will cover your scenarios?

[guybedford]

It works excellently, thanks @vladima for your work on this.

[guybedford]

Released in 0.13.2.