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/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';