[turbofan] Add support for copy-on-write element stores.

src/code-factory.cc

Index: src/code-factory.cc
diff --git a/src/code-factory.cc b/src/code-factory.cc
index 5078b19b030467639074fc2449140db4c5e1cfd7..bb59ab9aee9cd1ba66eda46c2d238bd4eacf1193 100644
--- a/src/code-factory.cc
+++ b/src/code-factory.cc
@@ -510,6 +510,12 @@ Callable CodeFactory::FastNewStrictArguments(Isolate* isolate,
 }
 
 // static
+Callable CodeFactory::CopyFixedArray(Isolate* isolate) {
+  return Callable(isolate->builtins()->CopyFixedArray(),
+                  CopyFixedArrayDescriptor(isolate));
+}
+
+// static
 Callable CodeFactory::AllocateHeapNumber(Isolate* isolate) {
   AllocateHeapNumberStub stub(isolate);
   return make_callable(stub);