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

runtime/vm/compiler.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/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 621 matching lines @@
   const char* function_fullname = function.ToFullyQualifiedCString();
   OS::Print("Code for %sfunction '%s' {\n",
             optimized ? "optimized " : "",
             function_fullname);
   const Code& code = Code::Handle(function.CurrentCode());
   code.Disassemble();
   OS::Print("}\n");
 
   OS::Print("Pointer offsets for function: {\n");
   // Pointer offsets are stored in descending order.
+  Object& obj = Object::Handle();
   for (intptr_t i = code.pointer_offsets_length() - 1; i >= 0; i--) {
     const uword addr = code.GetPointerOffsetAt(i) + code.EntryPoint();
-    Object& obj = Object::Handle();
     obj = *reinterpret_cast<RawObject**>(addr);
     OS::Print(" %d : %#" Px " '%s'\n",
               code.GetPointerOffsetAt(i), addr, obj.ToCString());
   }
   OS::Print("}\n");
 
   OS::Print("PC Descriptors for function '%s' {\n", function_fullname);
   PcDescriptors::PrintHeaderString();
   const PcDescriptors& descriptors =
       PcDescriptors::Handle(code.pc_descriptors());
@@ skipping 314 matching lines @@
     const Object& result =
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart