[runtime] Remove the redundant %_IsObject intrinsic.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 38271d37f6b12c55a342f7cb1d51289a317412e0..96c2af0fea17fa2da88abeec6ea7fb5bffc8cba4 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -12042,15 +12042,6 @@ void HOptimizedGraphBuilder::GenerateIsRegExp(CallRuntime* call) {
 }
 
 
-void HOptimizedGraphBuilder::GenerateIsObject(CallRuntime* call) {
-  DCHECK(call->arguments()->length() == 1);
-  CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
-  HValue* value = Pop();
-  HIsObjectAndBranch* result = New<HIsObjectAndBranch>(value);
-  return ast_context()->ReturnControl(result, call->id());
-}
-
-
 void HOptimizedGraphBuilder::GenerateToObject(CallRuntime* call) {
   DCHECK_EQ(1, call->arguments()->length());
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));