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

runtime/vm/intermediate_language_arm64.cc

Index: runtime/vm/intermediate_language_arm64.cc
===================================================================
--- runtime/vm/intermediate_language_arm64.cc	(revision 37955)
+++ runtime/vm/intermediate_language_arm64.cc	(working copy)
@@ -758,7 +758,7 @@
   const Register result = locs()->out(0).reg();
 
   // Push the result place holder initialized to NULL.
-  __ PushObject(Object::ZoneHandle(), PP);
+  __ PushObject(Object::null_object(), PP);
   // Pass a pointer to the first argument in R2.
   if (!function().HasOptionalParameters()) {
     __ AddImmediate(R2, FP, (kParamEndSlotFromFp +
@@ -2227,7 +2227,7 @@
 
   // 'instantiator_reg' is the instantiator TypeArguments object (or null).
   // A runtime call to instantiate the type is required.
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ PushObject(type(), PP);
   __ Push(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2295,7 +2295,7 @@
   __ Bind(&slow_case);
   // Instantiate non-null type arguments.
   // A runtime call to instantiate the type arguments is required.
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ PushObject(type_arguments(), PP);
   __ Push(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2350,7 +2350,7 @@
   const Register context_value = locs()->in(0).reg();
   const Register result = locs()->out(0).reg();
 
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ Push(context_value);
   compiler->GenerateRuntimeCall(token_pos(),
                                 deopt_id(),