Add an IC for CompareNil operations

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index f3a029ee340c79b043bbc7d239fb22cb6e4039b9..84bf81e9432ec7f7942ecf450018a082dff4e32b 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -3663,6 +3663,7 @@ int Code::major_key() {
          kind() == UNARY_OP_IC ||
          kind() == BINARY_OP_IC ||
          kind() == COMPARE_IC ||
+         kind() == COMPARE_NIL_IC ||
          kind() == LOAD_IC ||
          kind() == KEYED_LOAD_IC ||
          kind() == TO_BOOLEAN_IC);
@@ -3676,6 +3677,7 @@ void Code::set_major_key(int major) {
          kind() == UNARY_OP_IC ||
          kind() == BINARY_OP_IC ||
          kind() == COMPARE_IC ||
+         kind() == COMPARE_NIL_IC ||
          kind() == LOAD_IC ||
          kind() == KEYED_LOAD_IC ||
          kind() == STORE_IC ||
@@ -3892,6 +3894,12 @@ void Code::set_to_boolean_state(byte value) {
 }
 
 
+byte Code::compare_nil_state() {
+  ASSERT(is_compare_nil_ic_stub());
+  return extra_ic_state();
+}
+
+
 bool Code::has_function_cache() {
   ASSERT(kind() == STUB);
   return HasFunctionCacheField::decode(
@@ -5124,7 +5132,8 @@ void Code::set_type_feedback_info(Object* value, WriteBarrierMode mode) {
 
 
 int Code::stub_info() {
-  ASSERT(kind() == COMPARE_IC || kind() == BINARY_OP_IC || kind() == LOAD_IC);
+  ASSERT(kind() == COMPARE_IC || kind() == COMPARE_NIL_IC ||
+         kind() == BINARY_OP_IC || kind() == LOAD_IC);
   Object* value = READ_FIELD(this, kTypeFeedbackInfoOffset);
   return Smi::cast(value)->value();
 }
@@ -5132,6 +5141,7 @@ int Code::stub_info() {
 
 void Code::set_stub_info(int value) {
   ASSERT(kind() == COMPARE_IC ||
+         kind() == COMPARE_NIL_IC ||
          kind() == BINARY_OP_IC ||
          kind() == STUB ||
          kind() == LOAD_IC ||