build: turn on tsc's stripInternal when producint public d.ts file

I also made some changes to fix imports and remove some stuff that caused
breakage once stripInternals was turned on.

modules/@angular/common/src/directives.ts

@@ -10,5 +10,4 @@ export {NgTemplateOutlet} from './directives/ng_template_outlet';
 export {NgStyle} from './directives/ng_style';
 export {NgSwitch, NgSwitchWhen, NgSwitchDefault} from './directives/ng_switch';
 export {NgPlural, NgPluralCase, NgLocalization} from './directives/ng_plural';
-export * from './directives/observable_list_diff';
 export {CORE_DIRECTIVES} from './directives/core_directives';

modules/@angular/common/src/directives/observable_list_diff.ts

@@ -1,11 +0,0 @@
-// TS does not have Observables
-
-// I need to be here to make TypeScript think this is a module.
-import {} from '../../src/facade/lang';
-
-/**
- * This module exists in Dart, but not in Typescript. This exported symbol
- * is only here to help Typescript think this is a module.
- * @internal
- */
-export var workaround_empty_observable_list_diff: any;

modules/@angular/common/src/location/location.ts

@@ -1,5 +1,5 @@
-import {Injectable, Inject} from '@angular/core';
-import {EventEmitter, ObservableWrapper} from '../../src/facade/async';
+import {Injectable, EventEmitter} from '@angular/core';
+import {ObservableWrapper} from '../../src/facade/async';
 
 import {LocationStrategy} from './location_strategy';
 

modules/@angular/common/tsconfig-es2015.json

@@ -5,6 +5,7 @@
   "compilerOptions": {
     "baseUrl": ".",
     "declaration": true,
+    "stripInternal": true,
     "emitDecoratorMetadata": true,
     "experimentalDecorators": true,
     "module": "es2015",

modules/@angular/common/tsconfig-es5.json

@@ -5,6 +5,7 @@
   "compilerOptions": {
     "baseUrl": ".",
     "declaration": true,
+    "stripInternal": true,
     "emitDecoratorMetadata": true,
     "experimentalDecorators": true,
     "module": "commonjs",