Sourcemap - names array empty for all files

TypeScript Version: 1.8.34.0
Module System: AMD
ECMAScript Version: ECMAScript 5
VS 2015 Update 3

All of my map files have the names array empty. I would expect that to have been populated.
This has been an issue with VS2015 with all updates

Code

class HomeIndex {

    someVar: number;

    constructor() {
        this.someVar = 0;
    }

    onLoad = () => { 
    };

    dispose() {
    };

}

export = HomeIndex;

Generated map

{
  "version": 3,
  "file": "Index.js",
  "sourceRoot": "",
  "sources": [ "Index.ts" ],
  "names": [],
  "mappings": ";;IAAA;QAII;YAIA,WAAM,GAAG;YACT,CAAC,CAAC;YAJE,IAAI,CAAC,OAAO,GAAG,CAAC,CAAC;QACrB,CAAC;QAKD,2BAAO,GAAP;QACA,CAAC;;QAEL,gBAAC;IAAD,CAAC,AAdD,IAcC;IAED,OAAS,SAAS,CAAC"
}

Expected behavior:
names array should contain values for members and variables
Actual behavior:
names array empty

Start with the provided Index.ts example and generated Index.js sourcemap, reproducing it with TypeScript 1.8.34.0, AMD, and ECMAScript 5. Trace the sourcemap generation path and compare the sources, names, and mappings fields; done means the names array contains the emitted members and variables as expected.