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/@angular/platform-browser/src/browser/browser_adapter.ts

@@ -7,7 +7,6 @@
  */
 
 import {setRootDomAdapter} from '../dom/dom_adapter';
-import {ListWrapper} from '../facade/collection';
 import {DateWrapper, global, isBlank, isFunction, isPresent, setValueOnPath} from '../facade/lang';
 
 import {GenericBrowserDomAdapter} from './generic_browser_adapter';

modules/@angular/platform-browser/src/browser/location/browser_platform_location.ts

@@ -10,7 +10,6 @@ import {LocationChangeListener, PlatformLocation} from '@angular/common';
 import {Injectable} from '@angular/core';
 
 import {getDOM} from '../../dom/dom_adapter';
-import {History, Location} from '../../facade/browser';
 
 import {supportsState} from './history';
 

modules/@angular/platform-browser/src/browser/testability.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {GetTestability, Injectable, Testability, TestabilityRegistry, setTestabilityGetter} from '@angular/core';
+import {GetTestability, Testability, TestabilityRegistry, setTestabilityGetter} from '@angular/core';
 
 import {getDOM} from '../dom/dom_adapter';
 import {ListWrapper} from '../facade/collection';