Revert of [es6] Fix scoping for default parameters in arrow functions

src/ast-expression-visitor.h

Index: src/ast-expression-visitor.h
diff --git a/src/ast-expression-visitor.h b/src/ast-expression-visitor.h
index d9a4fc823863d527fd6aaa8ba3f642e5eeb75774..80bfa221717d544ef7c8e11d4613ad80c953dc03 100644
--- a/src/ast-expression-visitor.h
+++ b/src/ast-expression-visitor.h
@@ -21,8 +21,7 @@
 
 class AstExpressionVisitor : public AstVisitor {
  public:
-  AstExpressionVisitor(Isolate* isolate, Expression* root);
-  AstExpressionVisitor(uintptr_t stack_limit, Expression* root);
+  AstExpressionVisitor(Isolate* isolate, FunctionLiteral* root);
   void Run();
 
  protected:
@@ -39,7 +38,7 @@
   AST_NODE_LIST(DECLARE_VISIT)
 #undef DECLARE_VISIT
 
-  Expression* root_;
+  FunctionLiteral* root_;
   int depth_;
 
   DISALLOW_COPY_AND_ASSIGN(AstExpressionVisitor);