[turbofan] Add AllocateHeapNumberStub to avoid runtime call.

src/code-factory.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_CODE_FACTORY_H_
 #define V8_CODE_FACTORY_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
 #include "src/codegen.h"
@@ skipping 37 matching lines @@
   // code-stubs.h.
   static Callable ToBoolean(
       Isolate* isolate, ToBooleanStub::ResultMode mode,
       ToBooleanStub::Types types = ToBooleanStub::Types());
 
   static Callable ToNumber(Isolate* isolate);
 
   static Callable StringAdd(Isolate* isolate, StringAddFlags flags,
                             PretenureFlag pretenure_flag);
 
+  static Callable AllocateHeapNumber(Isolate* isolate);
+
   static Callable CallFunction(Isolate* isolate, int argc,
                                CallFunctionFlags flags);
 };
-}
-}
+
+}  // namespace internal
+}  // namespace v8
+
 #endif  // V8_CODE_FACTORY_H_