refactor: simplify arrow functions (#12057)

modules/@angular/core/test/animation/animation_integration_spec.ts

@@ -758,8 +758,7 @@ function declareTests({useJit}: {useJit: boolean}) {
       describe('*ngFor', () => {
         let tpl = '<div *ngFor="let item of items" @trigger>{{ item }}</div>';
 
-        let getText =
-            (node: any) => { return node.innerHTML ? node.innerHTML : node.children[0].data; };
+        let getText = (node: any) => node.innerHTML ? node.innerHTML : node.children[0].data;
 
         let assertParentChildContents = (parent: any, content: string) => {
           var values: string[] = [];

modules/@angular/core/test/change_detection/differs/default_iterable_differ_spec.ts

@@ -486,8 +486,7 @@ export function main() {
 
       var trackByItemId = (index: number, item: any): any => item.id;
 
-      var buildItemList =
-          (list: string[]) => { return list.map((val) => { return new ItemWithId(val); }); };
+      var buildItemList = (list: string[]) => list.map((val) => new ItemWithId(val));
 
       beforeEach(() => { differ = new DefaultIterableDiffer(trackByItemId); });
 

modules/@angular/core/test/zone/ng_zone_spec.ts

@@ -214,7 +214,7 @@ function commonTests() {
   describe('run', () => {
     it('should return the body return value from run',
        inject([AsyncTestCompleter], (async: AsyncTestCompleter) => {
-         macroTask(() => { expect(_zone.run(() => { return 6; })).toEqual(6); });
+         macroTask(() => { expect(_zone.run(() => 6)).toEqual(6); });
 
          macroTask(() => { async.done(); });
        }), testTimeout);