[stubs] Unify (and optimize) implementation of ToObject.

src/ia32/builtins-ia32.cc

Index: src/ia32/builtins-ia32.cc
diff --git a/src/ia32/builtins-ia32.cc b/src/ia32/builtins-ia32.cc
index 5e42f84696f4be7da130600d4e45ee1abc9091e6..c4509e200ed14d6620f8e10c16c7fc0e9d391ff4 100644
--- a/src/ia32/builtins-ia32.cc
+++ b/src/ia32/builtins-ia32.cc
@@ -994,8 +994,9 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
       __ SmiTag(eax);
       __ push(eax);
 
-      __ push(ebx);
-      __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
+      __ mov(eax, ebx);
+      ToObjectStub stub(masm->isolate());
+      __ CallStub(&stub);
       __ mov(ebx, eax);
       __ Move(edx, Immediate(0));  // restore
 
@@ -1215,8 +1216,9 @@ static void Generate_ApplyHelper(MacroAssembler* masm, bool targetIsArgument) {
     __ j(above_equal, &push_receiver);
 
     __ bind(&call_to_object);
-    __ push(ebx);
-    __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
+    __ mov(eax, ebx);
+    ToObjectStub stub(masm->isolate());
+    __ CallStub(&stub);
     __ mov(ebx, eax);
     __ jmp(&push_receiver);