Upstream the grammer for union types to idl_parser

tools/idl_parser/idl_parser.py

Index: tools/idl_parser/idl_parser.py
diff --git a/tools/idl_parser/idl_parser.py b/tools/idl_parser/idl_parser.py
index ff787a46346568708f03dd954ce6a6b326dacd0c..e022603da5230f5dfe29dfc404c3007a5e8a34c8 100755
--- a/tools/idl_parser/idl_parser.py
+++ b/tools/idl_parser/idl_parser.py
@@ -870,16 +870,28 @@ class IDLParser(object):
   # [75]
   def p_UnionType(self, p):
     """UnionType : '(' UnionMemberType OR UnionMemberType UnionMemberTypes ')'"""
+    members = ListFromConcat(p[2], p[4], p[5])
+    p[0] = self.BuildProduction('UnionType', p, 1, members)
 
   # [76]
   def p_UnionMemberType(self, p):
     """UnionMemberType : NonAnyType
                        | UnionType TypeSuffix
                        | ANY '[' ']' TypeSuffix"""
+    if len(p) == 2:
+      p[0] = self.BuildProduction('Type', p, 1, p[1])
+    elif len(p) == 3:
+      p[0] = self.BuildProduction('Type', p, 1, ListFromConcat(p[1], p[2]))
+    else:
+      any_node = ListFromConcat(self.BuildProduction('Any', p, 1), p[4])
+      p[0] = self.BuildProduction('Type', p, 1, any_node)
+
   # [77]
   def p_UnionMemberTypes(self, p):
     """UnionMemberTypes : OR UnionMemberType UnionMemberTypes
                         |"""
+    if len(p) > 2:
+      p[0] = ListFromConcat(p[2], p[3])
 
   # [78] Moved BYTESTRING, DOMSTRING, OBJECT, DATE, REGEXP to PrimitiveType
   # Moving all built-in types into PrimitiveType makes it easier to