Fix bug when the scanner does a pushback at the end of input.

src/scanner.cc

 // Copyright 2010 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 30 matching lines @@
 BufferedUC16CharacterStream::BufferedUC16CharacterStream()
     : UC16CharacterStream(),
       pushback_limit_(NULL) {
   // Initialize buffer as being empty. First read will fill the buffer.
   buffer_cursor_ = buffer_;
   buffer_end_ = buffer_;
 }
 
 BufferedUC16CharacterStream::~BufferedUC16CharacterStream() { }
 
-void BufferedUC16CharacterStream::PushBack(uc16 character) {
-  if (pushback_limit_ == NULL && buffer_cursor_ > buffer_) {
-    // buffer_ is writable, buffer_cursor_ is const pointer.
-    buffer_[--buffer_cursor_ - buffer_] = character;
+void BufferedUC16CharacterStream::PushBack(uc32 character) {
+  if (character == kEndOfInput) {
     pos_--;
     return;
   }
-  SlowPushBack(character);
+  if (pushback_limit_ == NULL && buffer_cursor_ > buffer_) {
+    // buffer_ is writable, buffer_cursor_ is const pointer.
+    buffer_[--buffer_cursor_ - buffer_] = static_cast<uc16>(character);
+    pos_--;
+    return;
+  }
+  SlowPushBack(static_cast<uc16>(character));
 }
 
 
 void BufferedUC16CharacterStream::SlowPushBack(uc16 character) {
   // In pushback mode, the end of the buffer contains pushback,
   // and the start of the buffer (from buffer start to pushback_limit_)
   // contains valid data that comes just after the pushback.
   // We NULL the pushback_limit_ if pushing all the way back to the
   // start of the buffer.
 
@@ skipping 484 matching lines @@
     text++;
   }
   if (ScannerConstants::kIsIdentifierPart.get(c0_)) return Token::ILLEGAL;
   literal.Complete();
   return token;
 }
 
 
 
 } }  // namespace v8::internal