Also delete force representations that have no uses.

src/hydrogen-representation-changes.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 60 matching lines @@
 
   new_value->InsertBefore(next);
   use_value->SetOperandAt(use_index, new_value);
 }
 
 
 void HRepresentationChangesPhase::InsertRepresentationChangesForValue(
     HValue* value) {
   Representation r = value->representation();
   if (r.IsNone()) return;
-  if (value->HasNoUses()) return;
+  if (value->HasNoUses()) {
+    if (value->IsForceRepresentation()) value->DeleteAndReplaceWith(NULL);
+    return;
+  }
 
   for (HUseIterator it(value->uses()); !it.Done(); it.Advance()) {
     HValue* use_value = it.value();
     int use_index = it.index();
     Representation req = use_value->RequiredInputRepresentation(use_index);
     if (req.IsNone() || req.Equals(r)) continue;
     InsertRepresentationChangeForUse(value, use_value, use_index, req);
   }
   if (value->HasNoUses()) {
     ASSERT(value->IsConstant());
@@ skipping 97 matching lines @@
     // Process normal instructions.
     for (HInstruction* current = block->first(); current != NULL; ) {
       HInstruction* next = current->next();
       InsertRepresentationChangesForValue(current);
       current = next;
     }
   }
 }
 
 } }  // namespace v8::internal