Backout a054d74dea39(Bug 766273) due to missing r= in comments

dom/system/gonk/ril_worker.js

@@ -1530,22 +1530,8 @@ let RIL = {
    */
   hangUp: function hangUp(options) {
     let call = this.currentCalls[options.callIndex];
-    if (!call) {
-      return;
-    }
-
-    switch (call.state) {
-      case CALL_STATE_ACTIVE:
-      case CALL_STATE_DIALING:
-      case CALL_STATE_ALERTING:
-        Buf.newParcel(REQUEST_HANGUP);
-        Buf.writeUint32(1);
-        Buf.writeUint32(options.callIndex);
-        Buf.sendParcel();
-        break;
-      case CALL_STATE_HOLDING:
-        Buf.simpleRequest(REQUEST_HANGUP_WAITING_OR_BACKGROUND);
-        break;
+    if (call && call.state != CALL_STATE_HOLDING) {
+      Buf.simpleRequest(REQUEST_HANGUP_FOREGROUND_RESUME_BACKGROUND);
     }
   },