Web MIDI: clean up on MIDIPort and MIDIErrorCallback

Source/modules/webmidi/MIDIPort.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 11 matching lines @@
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
-
 #include "modules/webmidi/MIDIPort.h"
 
 namespace WebCore {
 
 PassRefPtr<MIDIPort> MIDIPort::create(ScriptExecutionContext* context, const String& id, const String& manufacturer, const String& name, MIDIPortTypeCode type, const String& version)
 {
     RefPtr<MIDIPort> midiPort(adoptRef(new MIDIPort(context, id, manufacturer, name, type, version)));
     midiPort->suspendIfNeeded();
     return midiPort.release();
 }
@@ skipping 11 matching lines @@
 
 MIDIPort::~MIDIPort()
 {
     stop();
 }
 
 String MIDIPort::type() const
 {
     switch (m_type) {
     case MIDIPortTypeInput:
-        return "input";
+        return ASCIILiteral("input");
     case MIDIPortTypeOutput:
-        return "output";
+        return ASCIILiteral("output");
     default:
         ASSERT_NOT_REACHED();
     }
-    return "";
+    return emptyString();
 }
 
 } // namespace WebCore