Fix video code duplication.

rangeParams returned from getRangeParams() function is already
an object that contains the left and width properties. It can
be passed directly to the jQuery css() function.

common/lib/xmodule/xmodule/js/src/video/06_video_progress_slider.js

@@ -156,19 +156,13 @@ function () {
                        'ui-widget-header ' +
                        'ui-corner-all ' +
                        'slider-range'
-            }).css({
-                left: rangeParams.left,
-                width: rangeParams.width
-            });
+            }).css(rangeParams);
 
             this.videoProgressSlider.sliderProgress
                 .after(this.videoProgressSlider.sliderRange);
         } else {
             this.videoProgressSlider.sliderRange
-                .css({
-                    left: rangeParams.left,
-                    width: rangeParams.width
-                });
+                .css(rangeParams);
         }
     }