I fail to see the point to this, Silverlight was deprecated by Microsoft in favor of HTML5, end of story.
Silverlight is still also very heavily used for intranet apps (which is where http://www.telerik.com/ makes their money on Silverlight controls)
Browsers for mobiles (WebKit mostly) are very buggy and even have extra restrictions that desktop browsers do not. I doubt they did a better job with the engine on WP7.