Web MIDI: Add MIDIPortState state attribute to MIDIPort

Source/modules/webmidi/MIDIPort.idl

Index: Source/modules/webmidi/MIDIPort.idl
diff --git a/Source/modules/webmidi/MIDIPort.idl b/Source/modules/webmidi/MIDIPort.idl
index 902c825502541607f5a8e5079c002e7a344a142f..a316a86b26ea7add6c3e35f50fefae4396314131 100644
--- a/Source/modules/webmidi/MIDIPort.idl
+++ b/Source/modules/webmidi/MIDIPort.idl
@@ -28,6 +28,12 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+enum MIDIPortState {
+    "disconnected",
+    "connected",
+    "opened"
+};
+
 enum MIDIPortType {
     "input",
     "output"
@@ -40,6 +46,7 @@ enum MIDIPortType {
     readonly attribute DOMString id;
     readonly attribute DOMString manufacturer;
     readonly attribute DOMString name;
+    readonly attribute MIDIPortState state;
     readonly attribute MIDIPortType type;
     readonly attribute DOMString version;