Additional minor cleanup regarding CallWrapper: Use the null object pattern.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
===================================================================
--- src/ia32/lithium-codegen-ia32.cc	(revision 7766)
+++ src/ia32/lithium-codegen-ia32.cc	(working copy)
@@ -50,9 +50,9 @@
         deoptimization_index_(deoptimization_index) {}
   virtual ~SafepointGenerator() { }
 
-  virtual void BeforeCall(int call_size) {}
+  virtual void BeforeCall(int call_size) const {}
 
-  virtual void AfterCall() {
+  virtual void AfterCall() const {
     codegen_->RecordSafepoint(pointers_, deoptimization_index_);
   }
 
@@ -2552,7 +2552,7 @@
                                          pointers,
                                          env->deoptimization_index());
   ParameterCount actual(eax);
-  __ InvokeFunction(function, actual, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeFunction(function, actual, CALL_FUNCTION, safepoint_generator);
 }
 
 
@@ -2974,7 +2974,7 @@
   RegisterEnvironmentForDeoptimization(env);
   SafepointGenerator generator(this, pointers, env->deoptimization_index());
   ParameterCount count(instr->arity());
-  __ InvokeFunction(edi, count, CALL_FUNCTION, &generator);
+  __ InvokeFunction(edi, count, CALL_FUNCTION, generator);
 }
 
 
@@ -4237,7 +4237,7 @@
                                          env->deoptimization_index());
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
   __ push(Immediate(Smi::FromInt(strict_mode_flag())));
-  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, safepoint_generator);
 }
 
 
@@ -4297,7 +4297,7 @@
                                          pointers,
                                          env->deoptimization_index());
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
-  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }