[turbofan] Add AllocateHeapNumberStub to avoid runtime call.

src/code-factory.cc

Index: src/code-factory.cc
diff --git a/src/code-factory.cc b/src/code-factory.cc
index ae94fd5e9269c3b8ea5e254ed8acbcd59c255d94..e68d539207b2b32300a3b1e947e6e26be5cf8221 100644
--- a/src/code-factory.cc
+++ b/src/code-factory.cc
@@ -104,6 +104,13 @@ Callable CodeFactory::StringAdd(Isolate* isolate, StringAddFlags flags,
 
 
 // static
+Callable CodeFactory::AllocateHeapNumber(Isolate* isolate) {
+  AllocateHeapNumberStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+
+// static
 Callable CodeFactory::CallFunction(Isolate* isolate, int argc,
                                    CallFunctionFlags flags) {
   CallFunctionStub stub(isolate, argc, flags);