Also delete force representations that have no uses.

src/hydrogen-representation-changes.cc

Index: src/hydrogen-representation-changes.cc
diff --git a/src/hydrogen-representation-changes.cc b/src/hydrogen-representation-changes.cc
index 7d0720c6044d0d83dba8a61f867016e726a57128..0b87d12eb34ba0e24970d6489e18a13157c8c36c 100644
--- a/src/hydrogen-representation-changes.cc
+++ b/src/hydrogen-representation-changes.cc
@@ -78,7 +78,10 @@ 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();