[ic] Temporary resurrect ICStateField to recover performance regression.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 25e1d7d74b4c70993c4367a81e65a2270ecad947..914b80fb05dc9d964c37ee69e50685e9b540276c 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -5130,8 +5130,10 @@ Address Code::constant_pool() {
 
 Code::Flags Code::ComputeFlags(Kind kind, ExtraICState extra_ic_state,
                                CacheHolderFlag holder) {
+  // TODO(ishell): remove ICStateField.
   // Compute the bit mask.
   unsigned int bits = KindField::encode(kind) |
+                      ICStateField::encode(MONOMORPHIC) |
                       ExtraICStateField::encode(extra_ic_state) |
                       CacheHolderField::encode(holder);
   return static_cast<Flags>(bits);