Support Promise<T> syntax in the IDL parser.

tools/idl_parser/test_parser/struct_ppapi.idl

 /* Copyright (c) 2013 The Chromium Authors. All rights reserved.
    Use of this source code is governed by a BSD-style license that can be
   found in the LICENSE file. */
 
 /* Test Struct productions
 
 Run with --test to generate an AST and verify that all comments accurately
 reflect the state of the Nodes.
 
 BUILD Type(Name)
@@ skipping 24 matching lines @@
  *    Type()
  *      PrimitiveType(uint32_t)
  *  Member(y)
  *    Type()
  *      PrimitiveType(uint64_t)
  *  Member(string)
  *    ExtAttributes()
  *      ExtAttribute(fake_attribute)
  *    Type()
  *      PrimitiveType(str_t)
+ *  Member(z)
+ *    Type()
+ *      Typeref(Promise)
  *  ExtAttributes()
  *    ExtAttribute(union)
  */
 [union] struct MyStruct {
   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.

 };