[Transforms] export declaration for an import alias not emitted

[mhegazy]

Expected:

//// [t3.ts]
import a = require("./t1");
export { a }

//// [t3.js]
"use strict";
var a = require("./t1");
exports.a = a;

Actual

//// [t3.ts]
import a = require("./t1");
export { a }

//// [t3.js]
"use strict";
var a = require("./t1");

Failing tests:

• tests/cases/conformance/es6/modules/exportsAndImports4.ts
• tests/cases/conformance/es6/modules/exportsAndImports4-amd.ts
• tests/cases/conformance/es6/modules/exportsAndImports4-es6.ts