[stubs] Introduce AddStub and SubtractStub.

src/code-factory.cc

Index: src/code-factory.cc
diff --git a/src/code-factory.cc b/src/code-factory.cc
index 12645512c86fa859b4e5b2bc06054cdef60cf27b..1553e08da6d834aab7a81030862f553d08a00ef3 100644
--- a/src/code-factory.cc
+++ b/src/code-factory.cc
@@ -207,6 +207,18 @@ Callable CodeFactory::RegExpExec(Isolate* isolate) {
 }
 
 // static
+Callable CodeFactory::Add(Isolate* isolate) {
+  AddStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+// static
+Callable CodeFactory::Subtract(Isolate* isolate) {
+  SubtractStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+// static
 Callable CodeFactory::LessThan(Isolate* isolate) {
   LessThanStub stub(isolate);
   return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());