IDL parser: align with current Web IDL specification

tools/idl_parser/test_parser/enum_web.idl

Index: tools/idl_parser/test_parser/enum_web.idl
diff --git a/tools/idl_parser/test_parser/enum_web.idl b/tools/idl_parser/test_parser/enum_web.idl
index 233410c5d5dc8bcc6286db23f7c3d35c2a0d8b85..e3107c0ae41e64bd37e36220aef656b94c8a4984 100644
--- a/tools/idl_parser/test_parser/enum_web.idl
+++ b/tools/idl_parser/test_parser/enum_web.idl
@@ -67,6 +67,18 @@ enum MealType2 {
   "other"
 };
 
+/* TREE
+ *Enum(TrailingComma)
+ *  EnumItem(rice)
+ *  EnumItem(noodles)
+ *  EnumItem(other)
+*/
+enum TrailingComma {
+  "rice",
+  "noodles",
+  "other",
+};
+
 /* BUILD Error(Unexpected string "noodles" after string "rice".) */
 /* ERROR Unexpected string "noodles" after string "rice". */
 enum MissingComma {
@@ -75,14 +87,6 @@ enum MissingComma {
   "other"
 };
 
-/* BUILD Error(Trailing comma in block.) */
-/* ERROR Trailing comma in block. */
-enum TrailingComma {
-  "rice",
-  "noodles",
-  "other",
-};
-
 /* BUILD Error(Unexpected "," after ",".) */
 /* ERROR Unexpected "," after ",". */
 enum ExtraComma {