feat(core): Throw a descriptive error when BrowserModule is installed a second time (via lazy loading). (#10899)

Such a configuration is unsupported and causes all kinds of problems.

modules/@angular/platform-browser/src/browser.ts

@@ -7,7 +7,7 @@
  */
 
 import {CommonModule, PlatformLocation} from '@angular/common';
-import {ApplicationModule, ExceptionHandler, NgModule, PLATFORM_INITIALIZER, PlatformRef, Provider, RootRenderer, SanitizationService, Testability, createPlatformFactory, platformCore} from '@angular/core';
+import {ApplicationModule, BaseException, ExceptionHandler, NgModule, Optional, PLATFORM_INITIALIZER, PlatformRef, Provider, RootRenderer, SanitizationService, SkipSelf, Testability, createPlatformFactory, platformCore} from '@angular/core';
 
 import {wtfInit} from '../core_private';
 import {AnimationDriver} from '../src/dom/animation_driver';
@@ -93,4 +93,10 @@ export function _resolveDefaultAnimationDriver(): AnimationDriver {
   exports: [CommonModule, ApplicationModule]
 })
 export class BrowserModule {
+  constructor(@Optional() @SkipSelf() parentModule: BrowserModule) {
+    if (parentModule) {
+      throw new BaseException(
+          `BrowserModule has already been loaded. If you need access to common directives such as NgIf and NgFor from a lazy loaded module, import CommonModule instead.`);
+    }
+  }
 }

modules/@angular/platform-browser/test/browser/bootstrap_spec.ts

@@ -7,7 +7,7 @@
  */
 
 import {ResourceLoader} from '@angular/compiler';
-import {APP_INITIALIZER, CUSTOM_ELEMENTS_SCHEMA, Component, Directive, ExceptionHandler, Inject, Input, NgModule, OnDestroy, PLATFORM_INITIALIZER, Pipe, createPlatformFactory} from '@angular/core';
+import {APP_INITIALIZER, CUSTOM_ELEMENTS_SCHEMA, Compiler, Component, Directive, ExceptionHandler, Inject, Input, NgModule, OnDestroy, PLATFORM_INITIALIZER, Pipe, createPlatformFactory} from '@angular/core';
 import {ApplicationRef, destroyPlatform} from '@angular/core/src/application_ref';
 import {Console} from '@angular/core/src/console';
 import {ComponentRef} from '@angular/core/src/linker/component_factory';
@@ -216,6 +216,23 @@ export function main() {
          });
        }));
 
+    it('should throw a descriptive error if BrowserModule is installed again via a lazily loaded module',
+       inject([AsyncTestCompleter], (async: AsyncTestCompleter) => {
+         @NgModule({imports: [BrowserModule]})
+         class AsyncModule {
+         }
+         bootstrap(HelloRootCmp, testProviders)
+             .then((ref: ComponentRef<HelloRootCmp>) => {
+               let compiler: Compiler = ref.injector.get(Compiler);
+               return compiler.compileModuleAsync(AsyncModule).then(factory => {
+                 expect(() => factory.create(ref.injector))
+                     .toThrowError(
+                         `BrowserModule has already been loaded. If you need access to common directives such as NgIf and NgFor from a lazy loaded module, import CommonModule instead.`);
+               });
+             })
+             .then(() => async.done(), err => async.fail(err));
+       }));
+
     it('should support multiple calls to bootstrap',
        inject([AsyncTestCompleter], (async: AsyncTestCompleter) => {
          var refPromise1 = bootstrap(HelloRootCmp, testProviders);

tools/public_api_guard/platform-browser/index.d.ts

@@ -12,6 +12,7 @@ export declare const BROWSER_SANITIZATION_PROVIDERS: Array<any>;
 
 /** @experimental */
 export declare class BrowserModule {
+    constructor(parentModule: BrowserModule);
 }
 
 /** @stable */