Refactored jQuery.find() such that jQuery.nodeName() is used to test the node...

Refactored jQuery.find() such that jQuery.nodeName() is used to test the node names like .filter() and other functions do.  This puts in place possible fixes for tickets like #1991 where XML and HTML differ in case-sensitivity.

src/selector.js

@@ -122,12 +122,12 @@ jQuery.extend({
 			var m = re.exec(t);
 
 			if ( m ) {
-				var nodeName = m[1].toUpperCase();
+				var nodeName = m[1];
 
 				// Perform our own iteration and filter
 				for ( var i = 0; ret[i]; i++ )
 					for ( var c = ret[i].firstChild; c; c = c.nextSibling )
-						if ( c.nodeType == 1 && (nodeName == "*" || c.nodeName.toUpperCase() == nodeName.toUpperCase()) )
+						if ( c.nodeType == 1 && (nodeName == "*" || jQuery.nodeName(c, nodeName)) )
 							r.push( c );
 
 				ret = r;
@@ -151,7 +151,7 @@ jQuery.extend({
 
 								if ( m == "~" && merge[id] ) break;
 								
-								if (!nodeName || n.nodeName.toUpperCase() == nodeName.toUpperCase() ) {
+								if (!nodeName || jQuery.nodeName(n, nodeName)) {
 									if ( m == "~" ) merge[id] = true;
 									r.push( n );
 								}