fix(@angular/cli): fix broken vendor chunk default

Followup to #8077
Fix #8169

Author: filipesilva

packages/@angular/cli/commands/build.ts

@@ -215,11 +215,6 @@ const BuildCommand = Command.extend({
     Version.assertAngularVersionIs2_3_1OrHigher(this.project.root);
     Version.assertTypescriptVersion(this.project.root);
 
-    // Default vendor chunk to false when build optimizer is on.
-    if (commandOptions.vendorChunk === undefined) {
-      commandOptions.vendorChunk = !commandOptions.buildOptimizer;
-    }
-
     // Force commonjs module format for TS on dev watch builds.
     if (commandOptions.target === 'development' && commandOptions.watch === true) {
       commandOptions.forceTsCommonjs = true;

packages/@angular/cli/commands/eject.ts

@@ -33,11 +33,6 @@ const EjectCommand = Command.extend({
 
   run: function (commandOptions: EjectTaskOptions) {
 
-    // Default vendor chunk to false when build optimizer is on.
-    if (commandOptions.vendorChunk === undefined) {
-      commandOptions.vendorChunk = !commandOptions.buildOptimizer;
-    }
-
     const EjectTask = require('../tasks/eject').default;
     const ejectTask = new EjectTask({
       project: this.project,

packages/@angular/cli/commands/serve.ts

@@ -130,11 +130,6 @@ const ServeCommand = Command.extend({
     Version.assertAngularVersionIs2_3_1OrHigher(this.project.root);
     Version.assertTypescriptVersion(this.project.root);
 
-    // Default vendor chunk to false when build optimizer is on.
-    if (commandOptions.vendorChunk === undefined) {
-      commandOptions.vendorChunk = !commandOptions.buildOptimizer;
-    }
-
     // Force commonjs module format for TS on dev builds.
     if (commandOptions.target === 'development') {
       commandOptions.forceTsCommonjs = true;

packages/@angular/cli/models/webpack-config.ts

@@ -108,14 +108,23 @@ export class NgCliWebpackConfig<T extends BuildOptions = BuildOptions> {
       }
     };
 
-    const merged = Object.assign({}, targetDefaults[buildOptions.target], buildOptions);
+    let merged = Object.assign({}, targetDefaults[buildOptions.target], buildOptions);
 
     // Use Build Optimizer on prod AOT builds by default when AngularCompilerPlugin is supported.
-    const buildOptimizer = {
+    const buildOptimizerDefault = {
       buildOptimizer: merged.aot && AngularCompilerPlugin.isSupported()
     };
 
-    return Object.assign({}, buildOptimizer, merged);
+    merged = Object.assign({}, buildOptimizerDefault, merged);
+
+    // Default vendor chunk to false when build optimizer is on.
+    const vendorChunkDefault = {
+      vendorChunk: !merged.buildOptimizer
+    };
+
+    merged = Object.assign({}, vendorChunkDefault, merged);
+
+    return merged;
   }
 
   // Fill in defaults from .angular-cli.json