Revert of [es6] implement default parameters via desugaring

src/scopes.h

Index: src/scopes.h
diff --git a/src/scopes.h b/src/scopes.h
index 85ab773400a2b36b10c4848b534b2f2f6bb300cc..d56018532152909538635d95cdb50286ddfc0d34 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -126,7 +126,7 @@
   // parameters the rightmost one 'wins'.  However, the implementation
   // expects all parameters to be declared and from left to right.
   Variable* DeclareParameter(const AstRawString* name, VariableMode mode,
-                             bool is_rest, bool* is_duplicate, int pos);
+                             bool is_rest, bool* is_duplicate);
 
   // Declare a local variable in this scope. If the variable has been
   // declared before, the previously declared variable is returned.
@@ -181,10 +181,6 @@
   // this scope. The declarations are processed as part of entering
   // the scope; see codegen.cc:ProcessDeclarations.
   void AddDeclaration(Declaration* declaration);
-
-  // Formal parameters may be re-declared as lexical declarations in order to
-  // support TDZ semantics specified in ECMAScript 6.
-  void UndeclareParametersForExpressions();
 
   // ---------------------------------------------------------------------------
   // Illegal redeclaration support.
@@ -377,13 +373,6 @@
     return params_[index];
   }
 
-  // TODO(caitp): This probably won't work when BindingPatterns are supported
-  // in function parameters. Need a better way.
-  int parameter_position(int index) const {
-    DCHECK(is_function_scope());
-    return param_positions_[index];
-  }
-
   // Returns the default function arity --- does not include rest parameters.
   int default_function_length() const {
     int count = params_.length();
@@ -574,7 +563,6 @@
   ZoneList<Variable*> temps_;
   // Parameter list in source order.
   ZoneList<Variable*> params_;
-  ZoneList<int> param_positions_;
   // Variables that must be looked up dynamically.
   DynamicScopePart* dynamics_;
   // Unresolved variables referred to from this scope.
@@ -649,8 +637,6 @@
   Variable* rest_parameter_;
   int rest_index_;
 
-  bool has_parameter_expressions_;
-
   // Serialized scope info support.
   Handle<ScopeInfo> scope_info_;
   bool already_resolved() { return already_resolved_; }