[turbofan] Add AllocateHeapNumberStub to avoid runtime call.

src/code-factory.h

Index: src/code-factory.h
diff --git a/src/code-factory.h b/src/code-factory.h
index 2426cf0649dc4e06a01495fdd33b5930f7355b49..f26bf2a28e09aa16aee074d573f71f5b1634b6ed 100644
--- a/src/code-factory.h
+++ b/src/code-factory.h
@@ -55,9 +55,13 @@ class CodeFactory FINAL {
   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_