chore(lint): remove unused imports (#11923)

This was done automatically by tslint, which can now fix issues it finds.
The fixer is still pending in PR https://github.com/palantir/tslint/pull/1568
Also I have a local bugfix for https://github.com/palantir/tslint/issues/1569
which causes too many imports to be deleted.

modules/playground/src/web_workers/images/index_common.ts

@@ -7,7 +7,6 @@
  */
 
 import {Component} from '@angular/core';
-import {EventListener} from '@angular/core/src/facade/browser';
 
 import {FileReader, Uint8ArrayWrapper} from './file_api';
 import {BitmapService} from './services/bitmap';

modules/playground/src/web_workers/images/single_thread.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Component, NgModule} from '@angular/core';
+import {NgModule} from '@angular/core';
 import {BrowserModule} from '@angular/platform-browser';
 import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';