[turbofan] Properly unlink dead nodes in simplified lowering.

src/compiler/simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 1038 matching lines @@
       // same.
       node->ReplaceUses(replacement);
     } else {
       // Otherwise, we are replacing a node with a representation change.
       // Such a substitution must be done after all lowering is done, because
       // changing the type could confuse the representation change
       // insertion for uses of the node.
       replacements_.push_back(node);
       replacements_.push_back(replacement);
     }
-    // TODO(titzer) node->RemoveAllInputs();  // Node is now dead.
+    node->RemoveAllInputs();  // Node is now dead.
   }
 
   void PrintUseInfo(Node* node) {
     TRACE(("#%d:%-20s ", node->id(), node->op()->mnemonic()));
     PrintInfo(GetUseInfo(node));
     TRACE(("\n"));
   }
 
   void PrintInfo(MachineTypeUnion info) {
     if (FLAG_trace_representation) {
@@ skipping 503 matching lines @@
 
 void SimplifiedLowering::DoStringLessThanOrEqual(Node* node) {
   node->set_op(machine()->IntLessThanOrEqual());
   node->ReplaceInput(0, StringComparison(node, true));
   node->ReplaceInput(1, jsgraph()->SmiConstant(EQUAL));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8