refactor(@angular-devkit/build-angular): remove redundant isFirstRun check in Karma plugin

The Promise resolve function is idempotent. Removing the explicit 'isFirstRun' check simplifies the code as subsequent calls to resolve() after the first compilation will be ignored by the Promise.

Author: clydin

packages/angular_devkit/build_angular/src/tools/webpack/plugins/karma/karma.ts

@@ -85,7 +85,6 @@ const init: any = (config: any, emitter: any) => {
   });
 
   let lastCompilationHash: string | undefined;
-  let isFirstRun = true;
 
   return new Promise<void>((resolve) => {
     compiler.hooks.done.tap('karma', (stats) => {
@@ -115,14 +114,11 @@ const init: any = (config: any, emitter: any) => {
         emitter.refreshFiles();
       }
 
-      if (isFirstRun) {
-        // This is needed to block Karma from launching browsers before Webpack writes the assets in memory.
-        // See the below:
-        // https://github.com/karma-runner/karma-chrome-launcher/issues/154#issuecomment-986661937
-        // https://github.com/angular/angular-cli/issues/22495
-        isFirstRun = false;
-        resolve();
-      }
+      // This is needed to block Karma from launching browsers before Webpack writes the assets in memory.
+      // See the below:
+      // https://github.com/karma-runner/karma-chrome-launcher/issues/154#issuecomment-986661937
+      // https://github.com/angular/angular-cli/issues/22495
+      resolve();
     });
   });
 };