perf(compiler): skip type check and emit in bazel in some cases. (#19646)

If no user files changed:
- only type check the changed generated files

Never emit non changed generated files
- we still calculate them, but don’t send them through
  TypeScript to emit them but cache the written files instead.
PR Close #19646

packages/compiler-cli/src/transformers/node_emitter_transform.ts

@@ -9,6 +9,7 @@
 import {GeneratedFile} from '@angular/compiler';
 import * as ts from 'typescript';
 
+import {Program} from './api';
 import {TypeScriptNodeEmitter} from './node_emitter';
 import {GENERATED_FILES} from './util';
 
@@ -19,12 +20,12 @@ const PREAMBLE = `/**
 * tslint:disable
 */`;
 
-export function getAngularEmitterTransformFactory(generatedFiles: Map<string, GeneratedFile>): () =>
+export function getAngularEmitterTransformFactory(program: Program): () =>
     (sourceFile: ts.SourceFile) => ts.SourceFile {
   return function() {
     const emitter = new TypeScriptNodeEmitter();
     return function(sourceFile: ts.SourceFile): ts.SourceFile {
-      const g = generatedFiles.get(sourceFile.fileName);
+      const g = program.getGeneratedFile(sourceFile.fileName) as GeneratedFile;
       if (g && g.stmts) {
         const [newSourceFile] = emitter.updateSourceFile(sourceFile, g.stmts, PREAMBLE);
         return newSourceFile;