refactor(@angular-devkit/build-angular): optimize parallel worker shutdown

Stopping the workers can be a potentially lengthy process with a multi-stage approach based on the state of the worker.  This can cause lengthy blocking of the build.  This change allows the shutdown to happen in parallel to the remainder of the build.

Author: clydin

packages/angular_devkit/build_angular/src/browser/index.ts

@@ -570,7 +570,7 @@ export function buildWebpackBrowser(
                   }
                 }
               } finally {
-                await executor.stop();
+                executor.stop();
               }
 
               // Copy assets

packages/angular_devkit/build_angular/src/utils/action-executor.ts

@@ -144,12 +144,16 @@ export class BundleActionExecutor {
     }
   }
 
-  async stop(): Promise<void> {
+  stop(): void {
+    // Floating promises are intentional here
+    // https://github.com/facebook/jest/tree/56079a5aceacf32333089cea50c64385885fee26/packages/jest-worker#end
     if (this.largeWorker) {
-      await this.largeWorker.end();
+      // tslint:disable-next-line: no-floating-promises
+      this.largeWorker.end();
     }
     if (this.smallWorker) {
-      await this.smallWorker.end();
+      // tslint:disable-next-line: no-floating-promises
+      this.smallWorker.end();
     }
   }
 }

packages/angular_devkit/build_angular/src/utils/i18n-inlining.ts

@@ -112,7 +112,7 @@ export async function i18nInlineEmittedFiles(
 
     return false;
   } finally {
-    await executor.stop();
+    executor.stop();
   }
 
   if (hasErrors) {