[destructuring] Parse binding patterns in formal parameters.

src/preparser.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 531 matching lines @@
   do {
     // Parse binding pattern.
     if (nvars > 0) Consume(Token::COMMA);
     {
       ExpressionClassifier pattern_classifier;
       Token::Value next = peek();
       PreParserExpression pattern =
           ParsePrimaryExpression(&pattern_classifier, CHECK_OK);
       ValidateBindingPattern(&pattern_classifier, CHECK_OK);
 
-      if (!FLAG_harmony_destructuring && !pattern.IsIdentifier()) {
+      if (!allow_harmony_destructuring() && !pattern.IsIdentifier()) {
         ReportUnexpectedToken(next);
         *ok = false;
         return Statement::Default();
       }
     }
 
     Scanner::Location variable_loc = scanner()->location();
     nvars++;
     if (peek() == Token::ASSIGN || require_initializer ||
         // require initializers for multiple consts.
@@ skipping 621 matching lines @@
 
   DCHECK(!spread_pos.IsValid());
 
   return Expression::Default();
 }
 
 #undef CHECK_OK
 
 
 } }  // v8::internal