[runtime] Remove the redundant %_IsObject intrinsic.

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 715678cc750c30263e1253cf5ade88d6727f6f6f..7f81ea90d33eaede9bb51263b7121f6669bf5ad3 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -3256,38 +3256,6 @@ void FullCodeGenerator::EmitIsNonNegativeSmi(CallRuntime* expr) {
 }
 
 
-void FullCodeGenerator::EmitIsObject(CallRuntime* expr) {
-  ZoneList<Expression*>* args = expr->arguments();
-  DCHECK(args->length() == 1);
-
-  VisitForAccumulatorValue(args->at(0));
-
-  Label materialize_true, materialize_false;
-  Label* if_true = NULL;
-  Label* if_false = NULL;
-  Label* fall_through = NULL;
-  context()->PrepareTest(&materialize_true, &materialize_false,
-                         &if_true, &if_false, &fall_through);
-
-  __ JumpIfSmi(rax, if_false);
-  __ CompareRoot(rax, Heap::kNullValueRootIndex);
-  __ j(equal, if_true);
-  __ movp(rbx, FieldOperand(rax, HeapObject::kMapOffset));
-  // Undetectable objects behave like undefined when tested with typeof.
-  __ testb(FieldOperand(rbx, Map::kBitFieldOffset),
-           Immediate(1 << Map::kIsUndetectable));
-  __ j(not_zero, if_false);
-  __ movzxbp(rbx, FieldOperand(rbx, Map::kInstanceTypeOffset));
-  __ cmpp(rbx, Immediate(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-  __ j(below, if_false);
-  __ cmpp(rbx, Immediate(LAST_NONCALLABLE_SPEC_OBJECT_TYPE));
-  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-  Split(below_equal, if_true, if_false, fall_through);
-
-  context()->Plug(if_true, if_false);
-}
-
-
 void FullCodeGenerator::EmitIsSpecObject(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   DCHECK(args->length() == 1);