Make HForceRepresentation an idef.

src/hydrogen.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 2082 matching lines @@
 
   double nan_double = FixedDoubleArray::hole_nan_as_double();
   HValue* hole = IsFastSmiOrObjectElementsKind(elements_kind)
       ? Add<HConstant>(factory->the_hole_value())
       : Add<HConstant>(nan_double);
 
   // Special loop unfolding case
   static const int kLoopUnfoldLimit = 4;
   bool unfold_loop = false;
   int initial_capacity = JSArray::kPreallocatedArrayElements;
-  if (from->IsConstant() && to->IsConstant() &&
+  if (from->ActualValue()->IsConstant() && to->ActualValue()->IsConstant() &&
       initial_capacity <= kLoopUnfoldLimit) {
-    HConstant* constant_from = HConstant::cast(from);
-    HConstant* constant_to = HConstant::cast(to);
+    HConstant* constant_from = HConstant::cast(from->ActualValue());
+    HConstant* constant_to = HConstant::cast(to->ActualValue());
 
     if (constant_from->HasInteger32Value() &&
         constant_from->Integer32Value() == 0 &&
         constant_to->HasInteger32Value() &&
         constant_to->Integer32Value() == initial_capacity) {
       unfold_loop = true;
     }
   }
 
   // Since we're about to store a hole value, the store instruction below must
@@ skipping 8051 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal