cleanup: Renames a confusingly named field.

modules/statistics/RTPStatsCollector.js

         download: 0,
         upload: 0
     };
-    this.ssrc2resolution = {};
+    this.resolution = {};
 }
 
 /**
  * @param resolution new resolution value to be set.
  */
 PeerStats.prototype.setSsrcResolution = function (resolution) {
-    this.ssrc2resolution = resolution || {};
+    this.resolution = resolution || {};
 };
 
 /**
             ssrcStats.resetSsrcBitrate();
 
             // collect resolutions
-            resolutions[ssrc] = ssrcStats.ssrc2resolution;
+            resolutions[ssrc] = ssrcStats.resolution;
         },
         this
     );