Reapply revision 11570, custom callbacks are now implemented in dartium.

tests/html/html.status

Index: tests/html/html.status
diff --git a/tests/html/html.status b/tests/html/html.status
index a6b203f69c9573a9671a595f3ba6704b9eae525c..69d0274c4d5bc81129809680780fccbedc497a53 100644
--- a/tests/html/html.status
+++ b/tests/html/html.status
@@ -42,6 +42,8 @@ unknownelement_test: Fail # Issue 4189
 history_test: Fail
 
 [ $runtime == ie ]
+form_data_test: Fail # Issue 4793.
+form_element_test: Fail # Issue 4793.
 typed_arrays_1_test: Skip   # ie9 does not have typed arrays.
 typed_arrays_2_test: Skip
 typed_arrays_3_test: Skip