Support Promise<T> syntax in the IDL parser.

tools/idl_parser/test_parser/struct_ppapi.idl

Index: tools/idl_parser/test_parser/struct_ppapi.idl
diff --git a/tools/idl_parser/test_parser/struct_ppapi.idl b/tools/idl_parser/test_parser/struct_ppapi.idl
index dd017ac47f2e9def0dddae09063ca2ac1eab278a..59bc7eb8648698d261045711239edd4c76a4ddc7 100644
--- a/tools/idl_parser/test_parser/struct_ppapi.idl
+++ b/tools/idl_parser/test_parser/struct_ppapi.idl
@@ -42,6 +42,9 @@ symatics should exist.  This is an exact match.
  *      ExtAttribute(fake_attribute)
  *    Type()
  *      PrimitiveType(str_t)
+ *  Member(z)
+ *    Type()
+ *      Typeref(Promise)
  *  ExtAttributes()
  *    ExtAttribute(union)
  */
@@ -49,4 +52,5 @@ symatics should exist.  This is an exact match.
   uint32_t x;
   uint64_t y;
   [fake_attribute] str_t string;
+  Promise z;

[noelallen1, 2014/10/16 17:03:05]

Didn't you remove Promise from PPAPI parser/lexer?
This should be an error.

[Jens Widell, 2014/10/16 17:08:38]

Since it's not a keyword it's just another identifier. Why would this be an
error?

[noelallen1, 2014/10/16 18:14:02]

We should expect a type here.

def p_StructMember(self, p):
  """StructMember : ExtendedAttributeList Type identifier ';'"""

Promise an identifier.  It is neither a Type or Extended Attribute.  While
extended attributes list can be empty, this should fail to parse because Type is
required.

[Jens Widell, 2014/10/16 18:21:42]

But Type references NotAnyType (indirectly) which can be "identifier
TypeSuffix".

[noelallen1, 2014/10/16 18:36:25]

You are correct.  

Okay, I agree this is legal under the assumption that once the AST is created,
whatever is using it will error out if in fact 'Promise' has not been defined
via a typedef or some other form.

 };