Use kFunctionCid instead of kIllegalCid to indicate that a generic function

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 17592 matching lines @@
   }
   if (IsFinalized() == other_type_param.IsFinalized()) {
     return index() == other_type_param.index();
   }
   return name() == other_type_param.name();
 }
 
 
 void TypeParameter::set_parameterized_class(const Class& value) const {
   // Set value may be null.
-  classid_t cid = kIllegalCid;
+  classid_t cid = kFunctionCid;  // Denotes a function type parameter.
   if (!value.IsNull()) {
     cid = value.id();
   }
   StoreNonPointer(&raw_ptr()->parameterized_class_id_, cid);
 }
 
 
 classid_t TypeParameter::parameterized_class_id() const {
   return raw_ptr()->parameterized_class_id_;
 }
 
 
 RawClass* TypeParameter::parameterized_class() const {
   classid_t cid = parameterized_class_id();
-  if (cid == kIllegalCid) {
+  if (cid == kFunctionCid) {
     return Class::null();
   }
   return Isolate::Current()->class_table()->At(cid);
 }
 
 
 void TypeParameter::set_parameterized_function(const Function& value) const {
   StorePointer(&raw_ptr()->parameterized_function_, value.raw());
 }
 
@@ skipping 5127 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart