Remove invalid call to cef_popup_features_t_sizeof

Fixes set#41 (closed)

java/org.eclipse.set.browser.lib/src/org/eclipse/set/browser/lib/ChromiumLib.java

@@ -172,11 +172,6 @@ public class ChromiumLib extends C {
 	public static final native long allocate_cef_string_visitor_t(
 			Object handler);
 
-	/**
-	 * @return the size of cef_popup_features_t in bytes
-	 */
-	public static final native int cef_popup_features_t_sizeof();
-
 	/**
 	 * @param callback
 	 *            cast=(void *)