fix(@ngtools/webpack): wait for plugin when resolving ts requests

Fix angular#5137

Author: filipesilva

packages/@ngtools/webpack/src/plugin.ts

@@ -378,8 +378,11 @@ export class AotPlugin implements Tapable {
 
     compiler.plugin('after-resolvers', (compiler: any) => {
       // Virtual file system.
+      // Wait for the plugin to be done when requesting `.ts` files directly (entry points), or
+      // when the issuer is a `.ts` file.
       compiler.resolvers.normal.plugin('before-resolve', (request: any, cb: () => void) => {
-        if (request.request.match(/\.ts$/)) {
+        if (request.request.endsWith('.ts')
+          || (request.context.issuer && request.context.issuer.endsWith('.ts'))) {
           this.done!.then(() => cb(), () => cb());
         } else {
           cb();

tests/e2e/tests/build/aot/aot-rebuild.ts

@@ -0,0 +1,32 @@
+import {
+  killAllProcesses,
+  waitForAnyProcessOutputToMatch,
+  execAndWaitForOutputToMatch,
+} from '../../../utils/process';
+import { appendToFile, expectFileToMatch } from '../../../utils/fs';
+import { expectToFail } from '../../../utils/utils';
+import { getGlobalVariable } from '../../../utils/env';
+
+const validBundleRegEx = /webpack: bundle is now VALID|webpack: Compiled successfully./;
+
+export default function () {
+  if (process.platform.startsWith('win')) {
+    return Promise.resolve();
+  }
+  // Skip this in ejected tests.
+  if (getGlobalVariable('argv').eject) {
+    return Promise.resolve();
+  }
+
+  return execAndWaitForOutputToMatch('ng', ['build', '--watch'], validBundleRegEx)
+    // Check AOT templates are up to date with current code.
+    .then(() => expectToFail(() =>
+      expectFileToMatch('dist/main.bundle.js', '$$_E2E_GOLDEN_VALUE_1')))
+    .then(() => appendToFile('./src/app/app.component.html', '<p> $$_E2E_GOLDEN_VALUE_1 </p>'))
+    .then(() => waitForAnyProcessOutputToMatch(validBundleRegEx, 10000))
+    .then(() => expectFileToMatch('dist/main.bundle.js', '$$_E2E_GOLDEN_VALUE_1'))
+    .then(() => killAllProcesses(), (err: any) => {
+      killAllProcesses();
+      throw err;
+    });
+}