Encoding API: Handle null input string

Source/modules/encoding/TextEncoder.cpp

 /*
  * Copyright (C) 2013 Google Inc. 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
@@ skipping 66 matching lines @@
 
 PassRefPtr<Uint8Array> TextEncoder::encode(const String& input, const Dictionary& options)
 {
     bool stream = false;
     options.get("stream", stream);
 
     // FIXME: Not flushing is not supported by TextCodec for encode; add it or
     // handle split surrogates here.
 
     CString result;
-    if (input.is8Bit())
-        result = m_codec->encode(input.characters8(), input.length(), WTF::QuestionMarksForUnencodables);
-    else
-        result = m_codec->encode(input.characters16(), input.length(), WTF::QuestionMarksForUnencodables);
+    if (!input.isNull()) {
+        if (input.is8Bit())
+            result = m_codec->encode(input.characters8(), input.length(), WTF::QuestionMarksForUnencodables);
+        else
+            result = m_codec->encode(input.characters16(), input.length(), WTF::QuestionMarksForUnencodables);
+    }
 
     const char* buffer = result.data();
     const unsigned char* unsignedBuffer = reinterpret_cast<const unsigned char*>(buffer);
 
     return Uint8Array::create(unsignedBuffer, result.length());
 }
 
 } // namespace WebCore