fix(@angular/cli): fix empty space issue when setting angular-cli.json values

Close angular#5716

Author: sumitarora

packages/@ngtools/json-schema/src/serializers/json.ts

@@ -110,6 +110,11 @@ export class JsonSerializer implements Serializer {
 
  this._willOutputValue();
 
+ if (node.items.length === 0) {
+ this._writer('[]');
+ return;
+ }
+
  this._writer('[');
  this._state.push({ empty: true, type: 'array' });
  for (let i = 0; i < node.items.length; i++) {