Revert "Change the SSA construction pass to also construct def-use chains."

runtime/vm/flow_graph.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_FLOW_GRAPH_H_
 #define VM_FLOW_GRAPH_H_
 
 #include "vm/growable_array.h"
 #include "vm/intermediate_language.h"
 #include "vm/parser.h"
@@ skipping 106 matching lines @@
                     Environment* env,
                     Definition::UseKind use_kind);
   void InsertAfter(Instruction* prev,
                    Instruction* instr,
                    Environment* env,
                    Definition::UseKind use_kind);
 
   // Operations on the flow graph.
   void ComputeSSA(intptr_t next_virtual_register_number,
                   GrowableArray<Definition*>* inlining_parameters);
+  void ComputeUseLists();
 
   // Finds natural loops in the flow graph and attaches a list of loop
   // body blocks for each loop header.
   void ComputeLoops(GrowableArray<BlockEntryInstr*>* loop_headers);
 
   void RepairGraphAfterInlining();
 
   // TODO(zerny): Once the SSA is feature complete this should be removed.
   void Bailout(const char* reason) const;
 
   void InvalidateDominatorTree() { invalid_dominator_tree_ = true; }
 
 #ifdef DEBUG
-  // Verification methods for debugging.
+  // Validation methods for debugging.
+  bool ResetUseLists();
   bool VerifyUseLists();
 #endif  // DEBUG
 
  private:
   friend class ConstantPropagator;
 
   void DiscoverBlocks();
 
   // SSA transformation methods and fields.
   void ComputeDominators(GrowableArray<BitVector*>* dominance_frontier);
@@ skipping 38 matching lines @@
   GrowableArray<BlockEntryInstr*> preorder_;
   GrowableArray<BlockEntryInstr*> postorder_;
   GrowableArray<BlockEntryInstr*> reverse_postorder_;
   bool invalid_dominator_tree_;
   ConstantInstr* constant_null_;
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_H_