A decimal integer literal with a leading 0 is now an error in strict mode.

src/parsing/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_PARSING_PREPARSER_H
 #define V8_PARSING_PREPARSER_H
 
 #include "src/ast/scopes.h"
 #include "src/parsing/parser-base.h"
 
@@ skipping 855 matching lines @@
     int start_position = scanner()->peek_location().beg_pos;
     parsing_module_ = is_module;
     PreParserStatementList body;
     ParseStatementList(body, Token::EOS, &ok);
     if (stack_overflow()) return kPreParseStackOverflow;
     if (!ok) {
       ReportUnexpectedToken(scanner()->current_token());
     } else if (is_strict(this->scope()->language_mode())) {
       CheckStrictOctalLiteral(start_position, scanner()->location().end_pos,
                               &ok);
-      CheckDecimalLiteralWithLeadingZero(start_position,
-                                         scanner()->location().end_pos);
     }
     if (materialized_literals) {
       *materialized_literals = function_state_->materialized_literal_count();
     }
     return kPreParseSuccess;
   }
 
   // Parses a single function literal, from the opening parentheses before
   // parameters to the closing brace after the body.
   // Returns a FunctionEntry describing the body of the function in enough
@@ skipping 663 matching lines @@
     function_state_->NextMaterializedLiteralIndex();
     function_state_->NextMaterializedLiteralIndex();
   }
   return EmptyExpression();
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PREPARSER_H