Remove unused LivenessAnalyzer class.

src/ast.h

Index: src/ast.h
===================================================================
--- src/ast.h	(revision 4192)
+++ src/ast.h	(working copy)
@@ -196,10 +196,7 @@
     kTestValue
   };
 
-  Expression()
-      : bitfields_(0),
-        def_(NULL),
-        defined_vars_(NULL) {}
+  Expression() : bitfields_(0) {}
 
   virtual Expression* AsExpression()  { return this; }
 
@@ -233,15 +230,6 @@
   // Static type information for this expression.
   StaticType* type() { return &type_; }
 
-  // Data flow information.
-  DefinitionInfo* var_def() { return def_; }
-  void set_var_def(DefinitionInfo* def) { def_ = def; }
-
-  ZoneList<DefinitionInfo*>* defined_vars() { return defined_vars_; }
-  void set_defined_vars(ZoneList<DefinitionInfo*>* defined_vars) {
-    defined_vars_ = defined_vars;
-  }
-
   // AST analysis results
 
   // True if the expression rooted at this node can be compiled by the
@@ -284,9 +272,6 @@
   uint32_t bitfields_;
   StaticType type_;
 
-  DefinitionInfo* def_;
-  ZoneList<DefinitionInfo*>* defined_vars_;
-
   // Using template BitField<type, start, size>.
   class SideEffectFreeField : public BitField<bool, 0, 1> {};
   class NoNegativeZeroField : public BitField<bool, 1, 1> {};