fix: consistently rewrite Injector to INJECTOR (#23008)

In Ivy mode we rewrite references to Injector to INJECTOR in ngInjectableDef, to fix tree-shaking.

This changes the rewrite to happen always, even in non-Ivy mode, and makes Angular understand
INJECTOR across the board at runtime.

PR Close #23008

packages/compiler-cli/integrationtest/bazel/injectable_def/app/test/app_spec.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Component, Injectable, NgModule} from '@angular/core';
+import {Component, INJECTOR, Injectable, NgModule} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
 import {renderModuleFactory} from '@angular/platform-server';
 import {BasicAppModuleNgFactory} from 'app_built/src/basic.ngfactory';
@@ -142,4 +142,28 @@ describe('ngInjectableDef Bazel Integration', () => {
     TestBed.configureTestingModule({});
     expect(TestBed.get(Service).value).toEqual(true);
   });
+
+  it('NgModule injector understands requests for INJECTABLE', () => {
+    TestBed.configureTestingModule({
+      providers: [{provide: 'foo', useValue: 'bar'}],
+    });
+    expect(TestBed.get(INJECTOR).get('foo')).toEqual('bar');
+  });
+
+  it('Component injector understands requests for INJECTABLE', () => {
+    @Component({
+      selector: 'test-cmp',
+      template: 'test',
+      providers: [{provide: 'foo', useValue: 'bar'}],
+    })
+    class TestCmp {
+    }
+
+    TestBed.configureTestingModule({
+      declarations: [TestCmp],
+    });
+
+    const fixture = TestBed.createComponent(TestCmp);
+    expect(fixture.componentRef.injector.get(INJECTOR).get('foo')).toEqual('bar');
+  });
 });

packages/compiler/src/injectable_compiler.ts

@@ -63,7 +63,7 @@ export class InjectableCompiler {
       let tokenExpr: o.Expression;
       if (typeof token === 'string') {
         tokenExpr = o.literal(token);
-      } else if (token === this.tokenInjector && this.alwaysGenerateDef) {
+      } else if (token === this.tokenInjector) {
         tokenExpr = o.importExpr(Identifiers.INJECTOR);
       } else {
         tokenExpr = ctx.importExpr(token);

packages/core/src/di/injector.ts

@@ -145,7 +145,7 @@ export class StaticInjector implements Injector {
     records.set(
         Injector, <Record>{token: Injector, fn: IDENT, deps: EMPTY, value: this, useNew: false});
     records.set(
-        INJECTOR, <Record>{token: Injector, fn: IDENT, deps: EMPTY, value: this, useNew: false});
+        INJECTOR, <Record>{token: INJECTOR, fn: IDENT, deps: EMPTY, value: this, useNew: false});
     recursivelyProcessProviders(records, providers);
   }
 

packages/core/src/view/ng_module.ts

@@ -19,6 +19,7 @@ import {splitDepsDsl, tokenKey} from './util';
 const UNDEFINED_VALUE = new Object();
 
 const InjectorRefTokenKey = tokenKey(Injector);
+const INJECTORRefTokenKey = tokenKey(INJECTOR);
 const NgModuleRefTokenKey = tokenKey(NgModuleRef);
 
 export function moduleProvideDef(
@@ -86,6 +87,7 @@ export function resolveNgModuleDep(
   const tokenKey = depDef.tokenKey;
   switch (tokenKey) {
     case InjectorRefTokenKey:
+    case INJECTORRefTokenKey:
     case NgModuleRefTokenKey:
       return data;
   }

packages/core/src/view/provider.ts

@@ -7,12 +7,13 @@
  */
 
 import {ChangeDetectorRef, SimpleChange, SimpleChanges, WrappedValue} from '../change_detection/change_detection';
-import {Injector, resolveForwardRef} from '../di';
+import {INJECTOR, Injector, resolveForwardRef} from '../di';
 import {ElementRef} from '../linker/element_ref';
 import {TemplateRef} from '../linker/template_ref';
 import {ViewContainerRef} from '../linker/view_container_ref';
 import {Renderer as RendererV1, Renderer2} from '../render/api';
 import {stringify} from '../util';
+
 import {createChangeDetectorRef, createInjector, createRendererV1} from './refs';
 import {BindingDef, BindingFlags, DepDef, DepFlags, NodeDef, NodeFlags, OutputDef, OutputType, ProviderData, QueryValueType, Services, ViewData, ViewFlags, ViewState, asElementData, asProviderData, shouldCallLifecycleInitHook} from './types';
 import {calcBindingFlags, checkBinding, dispatchEvent, isComponentView, splitDepsDsl, splitMatchedQueriesDsl, tokenKey, viewParentEl} from './util';
@@ -24,6 +25,7 @@ const ViewContainerRefTokenKey = tokenKey(ViewContainerRef);
 const TemplateRefTokenKey = tokenKey(TemplateRef);
 const ChangeDetectorRefTokenKey = tokenKey(ChangeDetectorRef);
 const InjectorRefTokenKey = tokenKey(Injector);
+const INJECTORRefTokenKey = tokenKey(INJECTOR);
 
 export function directiveDef(
     checkIndex: number, flags: NodeFlags,
@@ -373,6 +375,7 @@ export function resolveDep(
           return createChangeDetectorRef(cdView);
         }
         case InjectorRefTokenKey:
+        case INJECTORRefTokenKey:
           return createInjector(searchView, elDef);
         default:
           const providerDef =