We removed deleteExpando after 1.4.2, for some reason. This caused problems with removeData() (no arguments). Fixes #7209.

src/support.js

@@ -61,6 +61,7 @@
 		optSelected: opt.selected,
 
 		// Will be defined later
+		deleteExpando: true,
 		optDisabled: false,
 		checkClone: false,
 		scriptEval: false,
@@ -91,6 +92,15 @@
 		delete window[ id ];
 	}
 
+	// Test to see if it's possible to delete an expando from an element
+	// Fails in Internet Explorer
+	try {
+		delete script.test;
+
+	} catch(e) {
+		jQuery.support.deleteExpando = false;
+	}
+
 	root.removeChild( script );
 
 	if ( div.attachEvent && div.fireEvent ) {