Don't mix handler flags into regular flag compuation.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index b17db2a71a1db56798cfe734efa7aaa8ce6135db..eb8a7565233cbae8965c465bb7b54af0856a1e01 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -5233,14 +5233,10 @@ class Code: public HeapObject {
 
   // [flags]: Access to specific code flags.
   inline Kind kind();
-  inline Kind handler_kind() {
-    return static_cast<Kind>(arguments_count());
-  }
   inline InlineCacheState ic_state();  // Only valid for IC stubs.
   inline ExtraICState extra_ic_state();  // Only valid for IC stubs.
 
   inline StubType type();  // Only valid for monomorphic IC stubs.
-  inline int arguments_count();  // Only valid for call IC stubs.
 
   // Testers for IC stub kinds.
   inline bool is_inline_cache_stub();
@@ -5379,22 +5375,25 @@ class Code: public HeapObject {
       InlineCacheState ic_state = UNINITIALIZED,
       ExtraICState extra_ic_state = kNoExtraICState,
       StubType type = NORMAL,
-      Kind handler_kind = STUB,
       InlineCacheHolderFlag holder = OWN_MAP);
 
   static inline Flags ComputeMonomorphicFlags(
       Kind kind,
       ExtraICState extra_ic_state = kNoExtraICState,
       InlineCacheHolderFlag holder = OWN_MAP,
+      StubType type = NORMAL);
+
+  static inline Flags ComputeHandlerFlags(
+      Kind handler_kind,
+      ExtraICState extra_ic_state = kNoExtraICState,
       StubType type = NORMAL,
-      Kind handler_kind = STUB);
+      InlineCacheHolderFlag holder = OWN_MAP);
 
   static inline InlineCacheState ExtractICStateFromFlags(Flags flags);
   static inline StubType ExtractTypeFromFlags(Flags flags);
   static inline Kind ExtractKindFromFlags(Flags flags);
   static inline InlineCacheHolderFlag ExtractCacheHolderFromFlags(Flags flags);
   static inline ExtraICState ExtractExtraICStateFromFlags(Flags flags);
-  static inline int ExtractArgumentsCountFromFlags(Flags flags);
 
   static inline Flags RemoveTypeFromFlags(Flags flags);
 
@@ -5614,11 +5613,9 @@ class Code: public HeapObject {
   class BackEdgesPatchedForOSRField: public BitField<bool,
       kIsCrankshaftedBit + 1 + 29, 1> {};  // NOLINT
 
-  // Signed field cannot be encoded using the BitField class.
-  static const int kArgumentsCountShift = 17;
-  static const int kArgumentsCountMask = ~((1 << kArgumentsCountShift) - 1);
-  static const int kArgumentsBits =
-      PlatformSmiTagging::kSmiValueSize - Code::kArgumentsCountShift + 1;
+  class HandlerKindField: public BitField<Kind, 17, 4> {};
+
+  static const int kArgumentsBits = 16;
   static const int kMaxArguments = (1 << kArgumentsBits) - 1;
 
   // This constant should be encodable in an ARM instruction.