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/e2e_test/sourcemap/sourcemap_spec.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import * as testUtil from 'e2e_util/e2e_util';
+
 
 var fs = require('fs');
 var sourceMap = require('source-map');