Fix mirror-script and debug tests when using external natives.

src/natives-external.cc

 // Copyright 2014 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.
 
 #include "src/natives.h"
 
 #include "src/base/logging.h"
 #include "src/list.h"
 #include "src/list-inl.h"
 #include "src/snapshot-source-sink.h"
@@ skipping 64 matching lines @@
 
  private:
   NativesStore() : debugger_count_(0) {}
 
   Vector<const char> NameFromId(const byte* id, int id_length) {
     Vector<char> name(Vector<char>::New(id_length + 11));
     SimpleStringBuilder builder(name.start(), name.length());
     builder.AddString("native ");
     builder.AddSubstring(reinterpret_cast<const char*>(id), id_length);
     builder.AddString(".js");
+    builder.Finalize();
+    // SimpleStringBuilder wants zero-byte; the caller does not.
+    DCHECK(name[name.length() - 1] == '\0');
+    name.Truncate(name.length() - 1);
     return Vector<const char>::cast(name);
   }
 
   bool ReadNameAndContentPair(SnapshotByteSource* bytes) {
     const byte* id;
     int id_length;
     const byte* source;
     int source_length;
     bool success = bytes->GetBlob(&id, &id_length) &&
                    bytes->GetBlob(&source, &source_length);
@@ skipping 92 matching lines @@
 }
 
 
 // The compiler can't 'see' all uses of the static methods and hence
 // my chose to elide them. This we'll explicitly instantiate these.
 template class NativesCollection<CORE>;
 template class NativesCollection<EXPERIMENTAL>;
 
 }  // namespace v8::internal
 }  // namespace v8