[strong] Deprecate ellisions

src/preparser.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_PREPARSER_H
 #define V8_PREPARSER_H
 
 #include "src/v8.h"
 
 #include "src/bailout-reason.h"
@@ skipping 1995 matching lines @@
   // ArrayLiteral ::
   //   '[' Expression? (',' Expression?)* ']'
 
   int pos = peek_position();
   typename Traits::Type::ExpressionList values =
       this->NewExpressionList(4, zone_);
   Expect(Token::LBRACK, CHECK_OK);
   while (peek() != Token::RBRACK) {
     ExpressionT elem = this->EmptyExpression();
     if (peek() == Token::COMMA) {
+      if (is_strong(language_mode())) {
+        ReportMessageAt(scanner()->peek_location(), "strong_ellision");
+        *ok = false;
+        return this->EmptyExpression();
+      }
       elem = this->GetLiteralTheHole(peek_position(), factory());
     } else {
       elem = this->ParseAssignmentExpression(true, CHECK_OK);
     }
     values->Add(elem, zone_);
     if (peek() != Token::RBRACK) {
       Expect(Token::COMMA, CHECK_OK);
     }
   }
   Expect(Token::RBRACK, CHECK_OK);
@@ skipping 1078 matching lines @@
       *ok = false;
       return;
     }
     has_seen_constructor_ = true;
     return;
   }
 }
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H