Use ParametrizedType instead of Type where appropriate. Expand ToCString of type related classes.

runtime/vm/class_finalizer.cc

 // Copyright (c) 2011, 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/class_finalizer.h"
 
 #include "vm/flags.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/longjump.h"
@@ skipping 688 matching lines @@
     isolate->set_long_jump_base(base);
     *errmsg = String::null();
     return canonical_type.raw();
   } else {
     // Error occured: Get the error message.
     isolate->set_long_jump_base(base);
     *errmsg = isolate->object_store()->sticky_error();
     return type.raw();
   }
   UNREACHABLE();
-  return Type::null();
+  return NULL;
 }
 
 
 void ClassFinalizer::ResolveAndFinalizeSignature(const Class& cls,
                                                  const Function& function) {
   // Resolve result type.
   Type& type = Type::Handle(function.result_type());
   if (!type.IsResolved()) {
     if (function.IsFactory()) {
       // The signature class of the factory for a generic class holds the type
@@ skipping 586 matching lines @@
   va_end(args);
   if (FLAG_warning_as_error) {
     Isolate::Current()->long_jump_base()->Jump(1, message_buffer);
     UNREACHABLE();
   } else {
     OS::Print(message_buffer);
   }
 }
 
 }  // namespace dart