Fix indexed access for DataTransferItemList

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

Index: tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate b/tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
index 54acce1e6ff548740df6ff0100314a7dd53cdd34..31455d62fa3a9e4cb31ee10a7f82ea102c2903d4 100644
--- a/tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
+++ b/tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
@@ -12,7 +12,10 @@ $!MEMBERS
 $if DART2JS
     return JS('DataTransferItem', '#[#]', this, index);
 $else
-    return __getter__(index);
+    // TODO(alanknight): I think that all the __getter__ generators should just
+    // do property access, but that's major surgery. This one is a problem, so
+    // just hard-code it for now.
+    return _blink.Blink_JsNative_DomException.getProperty(unwrap_jso(this), index);
 $endif
   }