Fix preparsing from a source string that is not external....

src/scanner.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 323 matching lines @@
 
 // ----------------------------------------------------------------------------
 // Scanner
 
 Scanner::Scanner(ParserMode pre)
     : is_pre_parsing_(pre == PREPARSE), stack_overflow_(false) { }
 
 
 void Scanner::Initialize(Handle<String> source,
                          ParserLanguage language) {
-  safe_string_input_buffer_.Reset(source.location());
-  Init(source, &safe_string_input_buffer_, 0, source->length(), language);
+  Init(source, NULL, 0, source->length(), language);
 }
 
 
 void Scanner::Initialize(Handle<String> source,
                          unibrow::CharacterStream* stream,
                          ParserLanguage language) {
   Init(source, stream, 0, kNoEndPosition, language);
 }
 
 
 void Scanner::Initialize(Handle<String> source,
                          int start_position,
                          int end_position,
                          ParserLanguage language) {
-  safe_string_input_buffer_.Reset(source.location());
-  Init(source, &safe_string_input_buffer_,
-       start_position, end_position, language);
+  Init(source, NULL, start_position, end_position, language);
 }
 
 
 void Scanner::Init(Handle<String> source,
                    unibrow::CharacterStream* stream,
                    int start_position,
                    int end_position,
                    ParserLanguage language) {
+  // Either initialize the scanner from a character stream or from a
+  // string.
+  ASSERT(source.is_null() || stream == NULL);
+
   // Initialize the source buffer.
   if (!source.is_null() && StringShape(*source).IsExternalTwoByte()) {
     two_byte_string_buffer_.Initialize(
         Handle<ExternalTwoByteString>::cast(source),
         start_position,
         end_position);
     source_ = &two_byte_string_buffer_;
   } else if (!source.is_null() && StringShape(*source).IsExternalAscii()) {
     ascii_string_buffer_.Initialize(
         Handle<ExternalAsciiString>::cast(source),
         start_position,
         end_position);
     source_ = &ascii_string_buffer_;
   } else {
+    if (!source.is_null()) {
+      safe_string_input_buffer_.Reset(source.location());
+      stream = &safe_string_input_buffer_;
+    }
     char_stream_buffer_.Initialize(source,
                                    stream,
                                    start_position,
                                    end_position);
     source_ = &char_stream_buffer_;
   }
 
   is_parsing_json_ = (language == JSON);
 
   // Set c0_ (one character ahead)
@@ skipping 937 matching lines @@
     }
     AddCharAdvance();
   }
   TerminateLiteral();
 
   next_.location.end_pos = source_pos() - 1;
   return true;
 }
 
 } }  // namespace v8::internal