Let NaN flow as double into HBranch

src/code-stubs.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1955 matching lines @@
     HEAP_NUMBER,
     NUMBER_OF_TYPES
   };
 
   // At most 8 different types can be distinguished, because the Code object
   // only has room for a single byte to hold a set of these types. :-P
   STATIC_ASSERT(NUMBER_OF_TYPES <= 8);
 
   class Types : public EnumSet<Type, byte> {
    public:
-    Types() {}
+    Types() : EnumSet<Type, byte>(0) {}
     explicit Types(byte bits) : EnumSet<Type, byte>(bits) {}
 
     byte ToByte() const { return ToIntegral(); }
     void Print(StringStream* stream) const;
     void TraceTransition(Types to) const;
     bool Record(Handle<Object> object);
     bool NeedsMap() const;
     bool CanBeUndetectable() const;
+    bool IsGeneric() const { return ToIntegral() == Generic().ToIntegral(); }
+
+    static Types Generic() { return Types((1 << NUMBER_OF_TYPES) - 1); }
   };
 
-  static Types no_types() { return Types(); }
-  static Types all_types() { return Types((1 << NUMBER_OF_TYPES) - 1); }
-
   explicit ToBooleanStub(Types types = Types())
       : types_(types) { }
   explicit ToBooleanStub(Code::ExtraICState state)
       : types_(static_cast<byte>(state)) { }
 
   bool Record(Handle<Object> object);
   Types GetTypes() { return types_; }
 
   virtual Handle<Code> GenerateCode();
   virtual void InitializeInterfaceDescriptor(
@@ skipping 155 matching lines @@
 
   // The current function entry hook.
   static FunctionEntryHook entry_hook_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileEntryHookStub);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CODE_STUBS_H_