refactor(compiler): remove private exports

All of `@angular/compiler` is private, so we can export
everything we need directly.

modules/@angular/compiler-cli/src/reflector_host.ts

@@ -6,12 +6,12 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {AssetUrl, ImportGenerator} from '@angular/compiler';
 import {AngularCompilerOptions, MetadataCollector, ModuleMetadata} from '@angular/tsc-wrapped';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as ts from 'typescript';
 
-import {AssetUrl, ImportGenerator} from './private_import_compiler';
 import {StaticReflectorHost, StaticSymbol} from './static_reflector';
 
 const EXT = /(\.ts|\.d\.ts|\.js|\.jsx|\.tsx)$/;