Use Object::null_object() instead of Object::ZoneHandle() when a null object

runtime/vm/parser.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/parser.h"
 
 #include "lib/invocation_mirror.h"
 #include "platform/utils.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
@@ skipping 1311 matching lines @@
     params.num_fixed_parameters++;
   }
   ASSERT(desc.PositionalCount() == params.num_fixed_parameters);
 
   // Named parameters.
   for (; i < desc.Count(); ++i) {
     ParamDesc p;
     intptr_t index = i - desc.PositionalCount();
     p.name = &String::ZoneHandle(I, desc.NameAt(index));
     p.type = &Type::ZoneHandle(I, Type::DynamicType());
-    p.default_value = &Object::ZoneHandle();
+    p.default_value = &Object::null_object();
     params.parameters->Add(p);
     params.num_optional_parameters++;
     params.has_optional_named_parameters = true;
   }
   ASSERT(desc.NamedCount() == params.num_optional_parameters);
 
   SetupDefaultsForOptionalParams(&params, default_values);
 
   // Build local scope for function and populate with the formal parameters.
   OpenFunctionBlock(func);
@@ skipping 347 matching lines @@
       SkipExpr();
     } else {
       const Object& const_value = ParseConstExpr()->literal();
       parameter.default_value = &const_value;
     }
   } else {
     if (params->has_optional_positional_parameters ||
         params->has_optional_named_parameters) {
       // Implicit default value is null.
       params->num_optional_parameters++;
-      parameter.default_value = &Object::ZoneHandle();
+      parameter.default_value = &Object::null_object();
     } else {
       params->num_fixed_parameters++;
       ASSERT(params->num_optional_parameters == 0);
     }
   }
   if (parameter.type->IsVoidType()) {
     ReportError("parameter '%s' may not be 'void'",
                 parameter.name->ToCString());
   }
   if (params->implicitly_final) {
@@ skipping 9348 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart