[compiler] Drop the CompareNilIC.

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 b442fc73f9d821eee7b26969c66753639c96431a..aa23cac3aeb58da4ab95a3a7719deea31ae86f94 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -3938,10 +3938,11 @@ void FullCodeGenerator::EmitLiteralCompareNil(CompareOperation* expr,
     __ CompareRoot(rax, nil_value);
     Split(equal, if_true, if_false, fall_through);
   } else {
-    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(), nil);
-    CallIC(ic, expr->CompareOperationFeedbackId());
-    __ CompareRoot(rax, Heap::kTrueValueRootIndex);
-    Split(equal, if_true, if_false, fall_through);
+    __ JumpIfSmi(rax, if_false);
+    __ movp(rax, FieldOperand(rax, HeapObject::kMapOffset));
+    __ testb(FieldOperand(rax, Map::kBitFieldOffset),
+             Immediate(1 << Map::kIsUndetectable));
+    Split(not_zero, if_true, if_false, fall_through);
   }
   context()->Plug(if_true, if_false);
 }