fix(@schematics/angular): Fix handling of returned promises

Avoid floating promises
Rationale: https://palantir.github.io/tslint/rules/no-floating-promises/

Author: apeeters

integration/angular_cli/e2e/src/app.e2e-spec.ts

@@ -8,9 +8,9 @@ describe('workspace-project App', () => {
     page = new AppPage();
   });
 
-  it('should display welcome message', () => {
-    page.navigateTo();
-    expect(page.getTitleText()).toEqual('integration-project app is running!');
+  it('should display welcome message', async () => {
+    await page.navigateTo();
+    await expect(await page.getTitleText()).toEqual('integration-project app is running!');
   });
 
   afterEach(async () => {

packages/angular_devkit/build_angular/test/hello-world-app/e2e/app.e2e-spec.ts

@@ -14,8 +14,8 @@ describe('hello-world-app App', () => {
     page = new AppPage();
   });
 
-  it('should display welcome message', () => {
-    page.navigateTo();
-    expect(page.getTitleText()).toEqual('Welcome to app!');
+  it('should display welcome message', async () => {
+    await page.navigateTo();
+    await expect(await page.getTitleText()).toEqual('Welcome to app!');
   });
 });

packages/schematics/angular/e2e/files/src/app.e2e-spec.ts.template

@@ -8,9 +8,9 @@ describe('workspace-project App', () => {
     page = new AppPage();
   });
 
-  it('should display welcome message', () => {
-    page.navigateTo();
-    expect(page.getTitleText()).toEqual('<%= relatedAppName %> app is running!');
+  it('should display welcome message', async () => {
+    await page.navigateTo();
+    await expect(await page.getTitleText()).toEqual('<%= relatedAppName %> app is running!');
   });
 
   afterEach(async () => {