[turbofan] Use CompareNilIC for abstract equality with null/undefined.

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index 80651b1588e0a14e1575e6cd2d6a252fc2cbbcfd..c0f9166da24b1740491a6d835a3e3f180932d8c5 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -2917,9 +2917,9 @@ void CompareNilIC::Clear(Address address, Code* target, Address constant_pool) {
 Handle<Object> CompareNilIC::DoCompareNilSlow(Isolate* isolate, NilValue nil,
                                               Handle<Object> object) {
   if (object->IsNull() || object->IsUndefined()) {
-    return handle(Smi::FromInt(true), isolate);
+    return isolate->factory()->true_value();
   }
-  return handle(Smi::FromInt(object->IsUndetectableObject()), isolate);
+  return isolate->factory()->ToBoolean(object->IsUndetectableObject());
 }