Data: avoid non-alphanumeric chars in expando properties

Ref chromium issue 378607
Ref #14839
Closes gh-1662

src/data/Data.js

@@ -14,7 +14,7 @@ function Data() {
 		}
 	});
 
-	this.expando = jQuery.expando + Math.random();
+	this.expando = jQuery.expando + Data.uid++;
 }
 
 Data.uid = 1;