properly export interface functions

Summary:
A TypeScript interface becomes a Closure function.
The previous code attempted to export that function when the
interface was exported, but due to
  microsoft/TypeScript#10122
it actually wasn't exporting.

You can see this in the new test goldens, where export.js now
includes "Bar" as an export.  (Bar is a TypeScript interface but
at the Closure level it is a value and must be in the module
exports.)

This also lets us remove a crazy forward declare hack that actually
wasn't necessary -- it was just working around that the export
wasn't working.

This matches the exporting behavior in d090fe4.

Reviewers: rkirov

Reviewed By: rkirov

Subscribers: typescript-eng

Differential Revision: https://reviews.angular.io/D213

Author: evmar

src/tsickle.ts

@@ -582,6 +582,7 @@ class Annotator extends ClosureRewriter {
     if (sym.flags & ts.SymbolFlags.Value) return;
 
     this.emit(`\n/** @record */\n`);
+    if (iface.flags & ts.NodeFlags.Export) this.emit('export ');
     let name = getIdentifierText(iface.name);
     this.emit(`function ${name}() {}\n`);
     if (iface.typeParameters) {
@@ -595,10 +596,6 @@ class Annotator extends ClosureRewriter {
     for (let elem of iface.members) {
       this.visitProperty(memberNamespace, elem);
     }
-
-    if (iface.flags & ts.NodeFlags.Export) {
-      this.emit(`export {${name}};\n`);
-    }
   }
 
   // emitTypeAnnotationsHelper produces a

test_files/export/export.js

@@ -1,6 +1,7 @@
 goog.module('test_files.export.export');var module = module || {id: 'test_files/export/export.js'};
 var export_helper_1 = goog.require('test_files.export.export_helper');
 exports.export2 = export_helper_1.export2;
+exports.Bar = export_helper_1.Bar;
 exports.export5 = export_helper_1.export5;
 exports.export4 = export_helper_1.export4;
 // These conflict with an export discovered via the above exports,

test_files/export/export_helper.tsickle.ts

@@ -4,10 +4,9 @@ export {export4} from './export_helper_2';
 export let /** @type {number} */ export1 = 3;
 export let /** @type {number} */ export2 = 3;
 /** @record */
-function Bar() {}
+export function Bar() {}
  /** @type {number} */
 Bar.prototype.barField;
-export {Bar};
 
 
 export interface Bar { barField: number; }

test_files/jsdoc_types/module1.tsickle.ts

@@ -1,8 +1,7 @@
 export class Class {}
 /** @record */
-function Interface() {}
+export function Interface() {}
  /** @type {number} */
 Interface.prototype.x;
-export {Interface};
 
 export interface Interface { x: number }

test_files/jsdoc_types/module2.tsickle.ts

@@ -1,10 +1,9 @@
 export class ClassOne {}
 export class ClassTwo {}
 /** @record */
-function Interface() {}
+export function Interface() {}
  /** @type {number} */
 Interface.prototype.x;
-export {Interface};
 
 export interface Interface { x: number }
 export class ClassWithParams<T> {}

test_files/jsdoc_types/nevertyped.tsickle.ts

@@ -1,9 +1,8 @@
 
 /** @record */
-function NeverTyped() {}
+export function NeverTyped() {}
  /** @type {number} */
 NeverTyped.prototype.foo;
-export {NeverTyped};
 /* This filename is specially marked in the tsickle test
  * suite runner so that its types are always {?}.*/