[turbofan] Move simplified alloc, load and store lowering to change lowering.

src/compiler/change-lowering.h

Index: src/compiler/change-lowering.h
diff --git a/src/compiler/change-lowering.h b/src/compiler/change-lowering.h
index ead41b1a004b67a8ec922d7a846b70e86213f006..6d607768d9c5d56cf4c16fb58c65326730c926b8 100644
--- a/src/compiler/change-lowering.h
+++ b/src/compiler/change-lowering.h
@@ -13,6 +13,7 @@ namespace compiler {
 
 // Forward declarations.
 class CommonOperatorBuilder;
+struct ElementAccess;
 class JSGraph;
 class Linkage;
 class MachineOperatorBuilder;
@@ -49,6 +50,13 @@ class ChangeLowering final : public Reducer {
                                Signedness signedness);
   Reduction ChangeUint32ToTagged(Node* value, Node* control);
 
+  Reduction LoadField(Node* node);
+  Reduction StoreField(Node* node);
+  Reduction LoadElement(Node* node);
+  Reduction StoreElement(Node* node);
+  Reduction Allocate(Node* node);
+
+  Node* ComputeIndex(const ElementAccess& access, Node* const key);
   Graph* graph() const;
   Isolate* isolate() const;
   JSGraph* jsgraph() const { return jsgraph_; }