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-dynamic/src/xhr/xhr_cache.ts

@@ -7,7 +7,7 @@
  */
 
 import {XHR} from '@angular/compiler';
-import {BaseException} from '../facade/exceptions';
+import {BaseException} from '@angular/core';
 import {global} from '../facade/lang';
 
 /**