make bgEventSegCss more dry

src/common/Grid.events.js

@@ -155,20 +155,9 @@ Grid.mixin({
 
 	// Generates a semicolon-separated CSS string to be used for the default rendering of a background event.
 	// Called by the fill system.
-	// TODO: consolidate with getEventSkinCss?
 	bgEventSegCss: function(seg) {
-		var view = this.view;
-		var event = seg.event;
-		var source = event.source || {};
-
 		return {
-			'background-color':
-				event.backgroundColor ||
-				event.color ||
-				source.backgroundColor ||
-				source.color ||
-				view.opt('eventBackgroundColor') ||
-				view.opt('eventColor')
+			'background-color': this.getSegSkinCss(seg)['background-color']
 		};
 	},