Fix bug that happens when the first non-ASCII character of a literal is at a power-of-two position.

src/scanner-base.h

 // 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 196 matching lines @@
     Vector<byte> new_store = Vector<byte>::New(NewCapacity(kInitialCapacity));
     memcpy(new_store.start(), backing_store_.start(), position_);
     backing_store_.Dispose();
     backing_store_ = new_store;
   }
 
   void ConvertToUC16() {
     ASSERT(is_ascii_);
     Vector<byte> new_store;
     int new_content_size = position_ * kUC16Size;
-    if (new_content_size > backing_store_.length()) {
+    if (new_content_size >= backing_store_.length()) {
+      // Ensure room for all currently read characters as UC16 as well
+      // as the character about to be stored.
       new_store = Vector<byte>::New(NewCapacity(new_content_size));
     } else {
       new_store = backing_store_;
     }
     char* src = reinterpret_cast<char*>(backing_store_.start());
     uc16* dst = reinterpret_cast<uc16*>(new_store.start());
     for (int i = position_ - 1; i >= 0; i--) {
       dst[i] = src[i];
     }
     if (new_store.start() != backing_store_.start()) {
@@ skipping 386 matching lines @@
   // keyword with the current prefix).
   const char* keyword_;
   int counter_;
   Token::Value keyword_token_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCANNER_BASE_H_