fix(@angular/cli): shut down after first Ctrl+C received

Fixes angular#9647

package.json

@@ -91,7 +91,6 @@
     "style-loader": "^0.19.1",
     "stylus": "^0.54.5",
     "stylus-loader": "^3.0.1",
-    "tree-kill": "^1.0.0",
     "typescript": "~2.6.2",
     "uglifyjs-webpack-plugin": "^1.1.8",
     "url-loader": "^0.6.2",
@@ -142,6 +141,7 @@
     "tar": "^4.1.1",
     "temp": "0.8.3",
     "through": "^2.3.6",
+    "tree-kill": "^1.0.0",
     "ts-node": "^4.1.0",
     "tslint": "^5.8.0",
     "zone.js": "^0.8.20"

packages/@ngtools/webpack/package.json

@@ -25,7 +25,6 @@
     "npm": ">= 3.0.0"
   },
   "dependencies": {
-    "tree-kill": "^1.0.0",
     "chalk": "~2.2.0",
     "loader-utils": "^1.0.2",
     "enhanced-resolve": "^3.1.0",

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

@@ -5,7 +5,6 @@ import * as path from 'path';
 import * as ts from 'typescript';
 
 const ContextElementDependency = require('webpack/lib/dependencies/ContextElementDependency');
-const treeKill = require('tree-kill');
 
 import { WebpackResourceLoader } from './resource_loader';
 import { WebpackCompilerHost } from './compiler_host';
@@ -507,26 +506,20 @@ export class AngularCompilerPlugin implements Tapable {
       forkOptions);
 
     // Handle child process exit.
-    const handleChildProcessExit = () => {
-      this._killForkedTypeChecker();
-      const msg = 'AngularCompilerPlugin: Forked Type Checker exited unexpectedly. ' +
-        'Falling back to type checking on main thread.';
-      this._warnings.push(msg);
-    };
-    this._typeCheckerProcess.once('exit', handleChildProcessExit);
-    this._typeCheckerProcess.once('SIGINT', handleChildProcessExit);
-    this._typeCheckerProcess.once('uncaughtException', handleChildProcessExit);
-
-    // Handle parent process exit.
-    const handleParentProcessExit = () => this._killForkedTypeChecker();
-    process.once('exit', handleParentProcessExit);
-    process.once('SIGINT', handleParentProcessExit);
-    process.once('uncaughtException', handleParentProcessExit);
+    this._typeCheckerProcess.on('exit', (_, signal) => {
+      this._typeCheckerProcess = undefined;
+      this._forkTypeChecker = false;
+      if (signal !== 'SIGTERM') {
+        const msg = 'AngularCompilerPlugin: Forked Type Checker exited unexpectedly. ' +
+          'Falling back to type checking on main thread.';
+        this._warnings.push(msg);
+      }
+    });
   }
 
   private _killForkedTypeChecker() {
-    if (this._typeCheckerProcess && this._typeCheckerProcess.pid) {
-      treeKill(this._typeCheckerProcess.pid, 'SIGTERM');
+    if (this._typeCheckerProcess) {
+      this._typeCheckerProcess.kill('SIGTERM');
       this._typeCheckerProcess = undefined;
       this._forkTypeChecker = false;
     }