Avoid problems when adding text which happens to match an Object method name.

Fixes #6779.

Author: cscott

src/manipulation.js

@@ -399,10 +399,12 @@ function buildFragment( args, nodes, scripts ) {
 	// IE 6 doesn't like it when you put <object> or <embed> elements in a fragment
 	// Also, WebKit does not clone 'checked' attributes on cloneNode, so don't cache
 	if ( args.length === 1 && typeof args[0] === "string" && args[0].length < 512 && doc === document &&
+		args[0] != 'hasOwnProperty' &&
 		!rnocache.test( args[0] ) && (jQuery.support.checkClone || !rchecked.test( args[0] )) ) {
 
 		cacheable = true;
-		cacheresults = jQuery.fragments[ args[0] ];
+		cacheresults = jQuery.fragments.hasOwnProperty(args[0]) ?
+                               jQuery.fragments[ args[0] ] : null;
 		if ( cacheresults ) {
 			if ( cacheresults !== 1 ) {
 				fragment = cacheresults;
@@ -599,4 +601,4 @@ function evalScript( i, elem ) {
 	if ( elem.parentNode ) {
 		elem.parentNode.removeChild( elem );
 	}
-}
+}