feat(ngUpgrade): add support for AoT compiled upgrade applications

This commit introduces a new API to the ngUpgrade module, which is compatible
with AoT compilation. Primarily, it removes the dependency on reflection
over the Angular 2 metadata by introducing an API where this information
is explicitly defined, in the source code, in a way that is not lost through
AoT compilation.

This commit is a collaboration between @mhevery (who provided the original
design of the API); @gkalpak & @petebacondarwin (who implemented the
API and migrated the specs from the original ngUpgrade tests) and @alexeagle
(who provided input and review).

This commit is an starting point, there is still work to be done:

* add more documentation
* validate the API via internal projects
* align the ngUpgrade compilation of A1 directives closer to the real A1
  compiler
* add more unit tests
* consider support for async `templateUrl` A1 upgraded components

Closes #12239

modules/@angular/upgrade/test/aot/integration/content_projection_spec.ts

@@ -0,0 +1,99 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {Component, Directive, ElementRef, Injector, NgModule, destroyPlatform} from '@angular/core';
+import {async} from '@angular/core/testing';
+import {BrowserModule} from '@angular/platform-browser';
+import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
+import {UpgradeComponent, UpgradeModule, downgradeComponent} from '@angular/upgrade';
+import * as angular from '@angular/upgrade/src/angular_js';
+
+import {bootstrap, html} from '../test_helpers';
+
+export function main() {
+  describe('content projection', () => {
+
+    beforeEach(() => destroyPlatform());
+    afterEach(() => destroyPlatform());
+
+    it('should instantiate ng2 in ng1 template and project content', async(() => {
+
+         // the ng2 component that will be used in ng1 (downgraded)
+         @Component({selector: 'ng2', template: `{{ 'NG2' }}(<ng-content></ng-content>)`})
+         class Ng2Component {
+         }
+
+         // our upgrade module to host the component to downgrade
+         @NgModule({
+           imports: [BrowserModule, UpgradeModule],
+           declarations: [Ng2Component],
+           entryComponents: [Ng2Component]
+         })
+         class Ng2Module {
+           ngDoBootstrap() {}
+         }
+
+         // the ng1 app module that will consume the downgraded component
+         const ng1Module = angular
+                               .module('ng1', [])
+                               // create an ng1 facade of the ng2 component
+                               .directive('ng2', downgradeComponent({component: Ng2Component}));
+
+         const element =
+             html('<div>{{ \'ng1[\' }}<ng2>~{{ \'ng-content\' }}~</ng2>{{ \']\' }}</div>');
+
+         bootstrap(platformBrowserDynamic(), Ng2Module, element, ng1Module).then((upgrade) => {
+           expect(document.body.textContent).toEqual('ng1[NG2(~ng-content~)]');
+         });
+       }));
+
+    it('should instantiate ng1 in ng2 template and project content', async(() => {
+
+         @Component({
+           selector: 'ng2',
+           template: `{{ 'ng2(' }}<ng1>{{'transclude'}}</ng1>{{ ')' }}`,
+         })
+         class Ng2Component {
+         }
+
+
+         @Directive({selector: 'ng1'})
+         class Ng1WrapperComponent extends UpgradeComponent {
+           constructor(elementRef: ElementRef, injector: Injector) {
+             super('ng1', elementRef, injector);
+           }
+         }
+
+         @NgModule({
+           declarations: [Ng1WrapperComponent, Ng2Component],
+           entryComponents: [Ng2Component],
+           imports: [BrowserModule, UpgradeModule]
+         })
+         class Ng2Module {
+           ngDoBootstrap() {}
+         }
+
+         const ng1Module = angular.module('ng1', [])
+                               .directive(
+                                   'ng1',
+                                   () => {
+                                     return {
+                                       transclude: true,
+                                       template: '{{ "ng1" }}(<ng-transclude></ng-transclude>)'
+                                     };
+                                   })
+                               .directive('ng2', downgradeComponent({component: Ng2Component}));
+
+         const element = html('<div>{{\'ng1(\'}}<ng2></ng2>{{\')\'}}</div>');
+
+         bootstrap(platformBrowserDynamic(), Ng2Module, element, ng1Module).then((upgrade) => {
+           expect(document.body.textContent).toEqual('ng1(ng2(ng1(transclude)))');
+         });
+       }));
+  });
+}