chore(imports): don't import ExceptionHandler from facade (#10620)

This lets us skip src/facade/exception* when compiling modules other than core.
It prevents having many conflicting declarations

modules/@angular/platform-browser/testing/benchmark_util.ts

@@ -6,9 +6,10 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {BaseException} from '@angular/core';
+
 import {BrowserDomAdapter} from '../src/browser/browser_adapter';
 import {document, window} from '../src/facade/browser';
-import {BaseException} from '../src/facade/exceptions';
 import {NumberWrapper, isBlank} from '../src/facade/lang';
 
 var DOM = new BrowserDomAdapter();