Reverts 774785 "Attempts to prevent blackness when switching simulcast streams."

It seems to break things when testing with multiple tabs open.

index.html

@@ -47,7 +47,7 @@
     <script src="analytics.js?v=1"></script><!-- google analytics plugin -->
     <script src="rtp_sts.js?v=3"></script><!-- RTP stats processing -->
     <script src="local_sts.js?v=2"></script><!-- Local stats processing -->
-    <script src="videolayout.js?v=19"></script><!-- video ui -->
+    <script src="videolayout.js?v=20"></script><!-- video ui -->
     <script src="connectionquality.js?v=1"></script>
     <script src="toolbar.js?v=6"></script><!-- toolbar ui -->
     <script src="toolbar_toggler.js?v=2"></script>

videolayout.js

@@ -227,13 +227,7 @@ var VideoLayout = (function (my) {
                 if (fade) {
                     $('#largeVideo').fadeOut(300, doUpdate);
                 } else {
-                    $("#preload").attr("src", largeVideoState.newSrc);
-                    // The 'canplay' event occurs when the browser can start
-                    // playing the specified audio/video. See:
-                    // http://www.w3schools.com/tags/av_event_canplay.asp
-                    $("#preload").one("canplay",function(){
-                        doUpdate();
-                    });
+                    doUpdate();
                 }
             }
         }