fix(@angular/cli): use an empty host for ng new

Creating the host means listing all files and directory. On large directories
it can be quite expensive. On ng new however we do not need to list everything,
only detect conflicts, so using an empty tree as the host of the schematics
makes sense.

Author: hansl

packages/@angular/cli/tasks/init.ts

@@ -78,6 +78,7 @@ export default Task.extend({
     const runOptions = {
       taskOptions: commandOptions,
       workingDir: cwd,
+      emptyHost: true,
       collectionName: commandOptions.collectionName,
       schematicName
     };

packages/@angular/cli/tasks/schematic-run.ts

@@ -1,6 +1,7 @@
 import {
   DryRunEvent,
   DryRunSink,
+  EmptyTree,
   FileSystemSink,
   FileSystemTree,
   Schematic,
@@ -22,6 +23,7 @@ const Task = require('../ember-cli/lib/models/task');
 export interface SchematicRunOptions {
   taskOptions: SchematicOptions;
   workingDir: string;
+  emptyHost: boolean;
   collectionName: string;
   schematicName: string;
 }
@@ -44,7 +46,7 @@ interface OutputLogging {
 
 export default Task.extend({
   run: function (options: SchematicRunOptions): Promise<SchematicOutput> {
-    const { taskOptions, workingDir, collectionName, schematicName } = options;
+    const { taskOptions, workingDir, emptyHost, collectionName, schematicName } = options;
 
     const ui = this.ui;
 
@@ -63,7 +65,8 @@ export default Task.extend({
     const preppedOptions = prepOptions(schematic, taskOptions);
     const opts = { ...taskOptions, ...preppedOptions };
 
-    const host = Observable.of(new FileSystemTree(new FileSystemHost(workingDir)));
+    const tree = emptyHost ? new EmptyTree() : new FileSystemTree(new FileSystemHost(workingDir));
+    const host = Observable.of(tree);
 
     const dryRunSink = new DryRunSink(workingDir, opts.force);
     const fsSink = new FileSystemSink(workingDir, opts.force);