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/compiler/test/metadata_resolver_spec.ts

@@ -14,7 +14,7 @@ import {
 
 import {IS_DART, stringify} from '../src/facade/lang';
 import {CompileMetadataResolver} from '../src/metadata_resolver';
-import {LifecycleHooks, LIFECYCLE_HOOKS_VALUES} from '@angular/core/src/metadata/lifecycle_hooks';
+import {LIFECYCLE_HOOKS_VALUES} from '@angular/core/src/metadata/lifecycle_hooks';
 import {
   Component,
   Directive,

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

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

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

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