Fix regression for "-200px" in animations; closes gh-822.

Also removes fake IIFEs ffrom effects.

src/effects.js

-(function( jQuery ) {
-
 var fxNow, timerId,
 	rfxtypes = /^(?:toggle|show|hide)$/,
-	rfxnum = /^([\-+]=)?((?:\d*\.)?\d+)([a-z%]*)$/i,
+	rfxnum = /^([+\-]=)?([\d+.\-]+)([a-z%]*)$/i,
 	rrun = /queueHooks$/,
 	animationPrefilters = [ defaultPrefilter ],
 	tweeners = {
@@ -633,5 +631,3 @@ if ( jQuery.expr && jQuery.expr.filters ) {
 		}).length;
 	};
 }
-
-})( jQuery );

test/unit/effects.js

@@ -197,6 +197,15 @@ test("animate negative margin", function() {
 	});
 });
 
+test("animate negative margin with px", function() {
+	expect(1);
+	stop();
+	jQuery("#foo").animate({ marginTop: "-100px" }, 100, function() {
+		equal( jQuery(this).css("marginTop"), "-100px", "Verify margin." );
+		start();
+	});
+});
+
 test("animate negative padding", function() {
 	expect(1);
 	stop();