Revert "Adding synchronous measurement methods to Element."

lib/html/templates/html/dart2js/impl_MouseEvent.darttemplate

Index: lib/html/templates/html/dart2js/impl_MouseEvent.darttemplate
diff --git a/lib/html/templates/html/dart2js/impl_MouseEvent.darttemplate b/lib/html/templates/html/dart2js/impl_MouseEvent.darttemplate
index 1af66662b25e7058a93496d8345c1f4cbd6e957c..63fa8471819937ecc4e498e1e197902a8f5cd788 100644
--- a/lib/html/templates/html/dart2js/impl_MouseEvent.darttemplate
+++ b/lib/html/templates/html/dart2js/impl_MouseEvent.darttemplate
@@ -15,7 +15,7 @@ $!MEMBERS
         throw const UnsupportedOperationException(
             'offsetX is only supported on elements');
       }
-      return this.clientX - this.target.getBoundingClientRect().left;
+      return this.clientX - this.target.$dom_getBoundingClientRect().left;
     }
   }
 
@@ -29,7 +29,7 @@ $!MEMBERS
         throw const UnsupportedOperationException(
             'offsetX is only supported on elements');
       }
-      return this.clientY - this.target.getBoundingClientRect().top;
+      return this.clientY - this.target.$dom_getBoundingClientRect().top;
     }
   }