Revert fx.show to always take opacity from 0 to current opacity value.

src/fx/fx.js

@@ -485,11 +485,10 @@ jQuery.extend({
 			// Remember where we started, so that we can go back to it later
 			z.el.orig[prop] = this.cur();
 			
+			var start = z.el.orig[prop];
+			
 			// Begin the animation
-			if (prop == "opacity")
-				z.custom(z.el.orig[prop], 1);
-			else
-				z.custom(0, z.el.orig[prop]);
+			z.custom(0, z.el.orig[prop]);
 
 			// Stupid IE, look what you made me do
 			if ( prop != "opacity" )