Get the name and message from DOMException correctly

tools/dom/templates/html/impl/impl_DOMException.darttemplate

Index: tools/dom/templates/html/impl/impl_DOMException.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_DOMException.darttemplate b/tools/dom/templates/html/impl/impl_DOMException.darttemplate
index 8b90d09ca27325e48ae5583450410690bc72ca05..5288a3d3e479f5e8478b7da259fccc34444b4e13 100644
--- a/tools/dom/templates/html/impl/impl_DOMException.darttemplate
+++ b/tools/dom/templates/html/impl/impl_DOMException.darttemplate
@@ -49,13 +49,6 @@ $if JSINTEROP
   // To suppress missing implicit constructor warnings.
   factory DomException._() { throw new UnsupportedError("Not supported"); }
 
-  @Deprecated("Internal Use Only")

[Jacob, 2017/06/08 23:50:00]

probably dead but do a text search of
third_party/webkit 
internalCreateDomException

to make sure we aren't calling this directly from C++

-  static DomException internalCreateDomException() {
-    return new DomException._internalWrap();
-  }
-
-  external factory DomException._internalWrap();
-
   @Deprecated("Internal Use Only")
   DomException.internal_() { }
 
@@ -73,15 +66,17 @@ $if JSINTEROP
 
   @DomName('DOMException.message')
   @DocsEditable()
-  String get message => _message;
+  String get message => _message ??
+     (_message = _blink.BlinkDOMException.instance.message_Getter_(this));
 
   @DomName('DOMException.name')
   @DocsEditable()
-  String get name => _name;
+  String get name => _name ??
+      (_name = _blink.BlinkDOMException.instance.name_Getter_(this));
 
   @DomName('DOMException.toString')
   @DocsEditable()
-  String toString() => "${_name}: $_message";
+  String toString() => "$name: $message";
 
 $else
 $!MEMBERS