[destructuring] Refactor duplicate parameter name detection.

src/parser.h

 // Copyright 2012 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.
 
 #ifndef V8_PARSER_H_
 #define V8_PARSER_H_
 
 #include "src/allocation.h"
 #include "src/ast.h"
 #include "src/compiler.h"  // TODO(titzer): remove this include dependency
@@ skipping 734 matching lines @@
   }
   ZoneList<ObjectLiteral::Property*>* NewPropertyList(int size, Zone* zone) {
     return new(zone) ZoneList<ObjectLiteral::Property*>(size, zone);
   }
   ZoneList<v8::internal::Statement*>* NewStatementList(int size, Zone* zone) {
     return new(zone) ZoneList<v8::internal::Statement*>(size, zone);
   }
   V8_INLINE Scope* NewScope(Scope* parent_scope, ScopeType scope_type,
                             FunctionKind kind = kNormalFunction);
 
-  bool DeclareFormalParameter(Scope* scope, const AstRawString* name,
-                              bool is_rest) {
-    bool is_duplicate = false;
-    Variable* var = scope->DeclareParameter(name, VAR, is_rest, &is_duplicate);
-    if (is_sloppy(scope->language_mode())) {
-      // TODO(sigurds) Mark every parameter as maybe assigned. This is a
-      // conservative approximation necessary to account for parameters
-      // that are assigned via the arguments array.
-      var->set_maybe_assigned();
-    }
-    return is_duplicate;
-  }
-
+  V8_INLINE void DeclareFormalParameter(Scope* scope, const AstRawString* name,
+                                        ExpressionClassifier* classifier,
+                                        bool is_rest);
   void DeclareArrowFunctionParameters(Scope* scope, Expression* expr,
                                       const Scanner::Location& params_loc,
                                       Scanner::Location* duplicate_loc,
                                       bool* ok);
   void ParseArrowFunctionFormalParameters(Scope* scope, Expression* params,
                                           const Scanner::Location& params_loc,
                                           bool* is_rest,
                                           Scanner::Location* duplicate_loc,
                                           bool* ok);
 
@@ skipping 495 matching lines @@
                                      ZoneList<v8::internal::Expression*>* args,
                                      int pos) {
   return parser_->SpreadCall(function, args, pos);
 }
 
 
 Expression* ParserTraits::SpreadCallNew(
     Expression* function, ZoneList<v8::internal::Expression*>* args, int pos) {
   return parser_->SpreadCallNew(function, args, pos);
 }
+
+
+void ParserTraits::DeclareFormalParameter(Scope* scope,
+                                          const AstRawString* name,
+                                          ExpressionClassifier* classifier,
+                                          bool is_rest) {
+  bool is_duplicate = false;
+  Variable* var = scope->DeclareParameter(name, VAR, is_rest, &is_duplicate);
+  if (is_sloppy(scope->language_mode())) {
+    // TODO(sigurds) Mark every parameter as maybe assigned. This is a
+    // conservative approximation necessary to account for parameters
+    // that are assigned via the arguments array.
+    var->set_maybe_assigned();
+  }
+  if (is_duplicate) {
+    classifier->RecordDuplicateFormalParameterError(
+        parser_->scanner()->location());
+  }
+}
 } }  // namespace v8::internal
 
 #endif  // V8_PARSER_H_