Opera 12.0 still implements an older version of the DOM so cloneNode …

…cannot be called without an argument

src/support.js

@@ -65,7 +65,7 @@ jQuery.support = (function() {
 	support.focusinBubbles = "onfocusin" in window || div.attributes.onfocusin.expando === false;
 
 	div.style.backgroundClip = "content-box";
-	div.cloneNode().style.backgroundClip = "";
+	div.cloneNode( true ).style.backgroundClip = "";
 	support.clearCloneStyle = div.style.backgroundClip === "content-box";
 
 	// Run tests that need a body at doc ready