[turbofan] Add support for transitioning stores to double fields.

src/code-factory.cc

Index: src/code-factory.cc
diff --git a/src/code-factory.cc b/src/code-factory.cc
index 37179f38c938c27b9e4e21b165575c94fbeccae9..89e96519f44bb86a9ebdca615cacd127aacfe18b 100644
--- a/src/code-factory.cc
+++ b/src/code-factory.cc
@@ -274,6 +274,13 @@ Callable CodeFactory::AllocateHeapNumber(Isolate* isolate) {
 
 
 // static
+Callable CodeFactory::AllocateMutableHeapNumber(Isolate* isolate) {
+  AllocateMutableHeapNumberStub stub(isolate);
+  return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());
+}
+
+
+// static
 Callable CodeFactory::AllocateInNewSpace(Isolate* isolate) {
   AllocateInNewSpaceStub stub(isolate);
   return Callable(stub.GetCode(), stub.GetCallInterfaceDescriptor());