Make sure that calling .width(num) or .height(num) on an empty set returns the...

Make sure that calling .width(num) or .height(num) on an empty set returns the empty set. Fixes #5600.

src/dimensions.js

@@ -20,7 +20,10 @@ jQuery.each([ "Height", "Width" ], function(i, name){
 	jQuery.fn[ type ] = function( size ) {
 		// Get window width or height
 		var elem = this[0];
-		if ( !elem ) { return null; }
+		if ( !elem ) {
+			return size == null ? null : this;
+		}
+
 		return ("scrollTo" in elem && elem.document) ? // does it walk and quack like a window?
 			// Everyone else use document.documentElement or document.body depending on Quirks vs Standards mode
 			elem.document.compatMode === "CSS1Compat" && elem.document.documentElement[ "client" + name ] ||

test/unit/dimensions.js

 module("dimensions");
 
 test("width()", function() {
-	expect(6);
+	expect(7);
 
 	var $div = jQuery("#nothiddendiv");
 	$div.width(30);
@@ -28,10 +28,13 @@ test("width()", function() {
 	jQuery("#nothiddendivchild").css({ padding: "3px", border: "2px solid #fff" });
 	equals(jQuery("#nothiddendivchild").width(), 20, "Test child width with border and padding");
 	jQuery("#nothiddendiv, #nothiddendivchild").css({ border: "", padding: "", width: "" });
+
+	var blah = jQuery("blah");
+	equals( blah.width(10), blah, "Make sure that setting a width on an empty set returns the set." );
 });
 
 test("height()", function() {
-	expect(5);
+	expect(6);
 
 	var $div = jQuery("#nothiddendiv");
 	$div.height(30);
@@ -54,6 +57,9 @@ test("height()", function() {
 	//equals($div.height(), 30, "Test padding specified with percent");
 
 	$div.css({ display: "", border: "", padding: "", height: "1px" });
+
+	var blah = jQuery("blah");
+	equals( blah.height(10), blah, "Make sure that setting a height on an empty set returns the set." );
 });
 
 test("innerWidth()", function() {