Revert changes 4088 and 4087 to fix build.

src/data-flow.h

 // Copyright 2010 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 25 matching lines @@
 
 namespace v8 {
 namespace internal {
 
 class BitVector: public ZoneObject {
  public:
   explicit BitVector(int length)
       : length_(length),
         data_length_(SizeFor(length)),
         data_(Zone::NewArray<uint32_t>(data_length_)) {
+    ASSERT(length > 0);
     Clear();
   }
 
   BitVector(const BitVector& other)
       : length_(other.length()),
         data_length_(SizeFor(length_)),
         data_(Zone::NewArray<uint32_t>(data_length_)) {
     CopyFrom(other);
   }
 
@@ skipping 422 matching lines @@
   AST_NODE_LIST(DECLARE_VISIT)
 #undef DECLARE_VISIT
 
   // Map for tracking the live variables.
   VarUseMap live_vars_;
 
   DISALLOW_COPY_AND_ASSIGN(LivenessAnalyzer);
 };
 
 
-// Computes the set of assigned variables and annotates variables proxies
-// that are trivial sub-expressions and for-loops where the loop variable
-// is guaranteed to be a smi.
-class AssignedVariablesAnalyzer : public AstVisitor {
- public:
-  explicit AssignedVariablesAnalyzer(FunctionLiteral* fun);
-
-  void Analyze();
-
- private:
-  Variable* FindSmiLoopVariable(ForStatement* stmt);
-
-  int BitIndex(Variable* var);
-
-  void RecordAssignedVar(Variable* var);
-
-  void MarkIfTrivial(Expression* expr);
-
-  // Visits an expression saving the accumulator before, clearing
-  // it before visting and restoring it after visiting.
-  void ProcessExpression(Expression* expr);
-
-  // AST node visit functions.
-#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
-  AST_NODE_LIST(DECLARE_VISIT)
-#undef DECLARE_VISIT
-
-  FunctionLiteral* fun_;
-
-  // Accumulator for assigned variables set.
-  BitVector av_;
-
-  DISALLOW_COPY_AND_ASSIGN(AssignedVariablesAnalyzer);
-};
-
 } }  // namespace v8::internal
 
 
 #endif  // V8_DATAFLOW_H_