Fix adding short external ascii strings...

src/heap.cc

 // Copyright 2009 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 1801 matching lines @@
   // If the resulting string is small make a flat string.
   if (length < String::kMinNonFlatLength) {
     ASSERT(first->IsFlat());
     ASSERT(second->IsFlat());
     if (is_ascii) {
       Object* result = AllocateRawAsciiString(length);
       if (result->IsFailure()) return result;
       // Copy the characters into the new object.
       char* dest = SeqAsciiString::cast(result)->GetChars();
       // Copy first part.
-      char* src = SeqAsciiString::cast(first)->GetChars();
+      const char* src;
+      if (first->IsExternalString()) {
+        src = ExternalAsciiString::cast(first)->resource()->data();
+      } else {
+        src = SeqAsciiString::cast(first)->GetChars();
+      }
       for (int i = 0; i < first_length; i++) *dest++ = src[i];
       // Copy second part.
-      src = SeqAsciiString::cast(second)->GetChars();
+      if (second->IsExternalString()) {
+        src = ExternalAsciiString::cast(second)->resource()->data();
+      } else {
+        src = SeqAsciiString::cast(second)->GetChars();
+      }
       for (int i = 0; i < second_length; i++) *dest++ = src[i];
       return result;
     } else {
       Object* result = AllocateRawTwoByteString(length);
       if (result->IsFailure()) return result;
       // Copy the characters into the new object.
       uc16* dest = SeqTwoByteString::cast(result)->GetChars();
       String::WriteToFlat(first, dest, 0, first_length);
       String::WriteToFlat(second, dest + first_length, 0, second_length);
       return result;
@@ skipping 2120 matching lines @@
   for (int i = 0; i < kNumberOfCaches; i++) {
     if (caches_[i] != NULL) {
       delete caches_[i];
       caches_[i] = NULL;
     }
   }
 }
 
 
 } }  // namespace v8::internal