WCPasteboard.initIDs() fails after fix for RT-26480

Method WCPasteboard.clear() was removed as part of RT-26480. However in native method initIDs() we still try to initialize the method handle.

To reproduce, try to copy any text from WebView with Ctrl+C. An exception will be thrown:
    java.lang.NoClassDefFoundError: Could not initialize class com.sun.webkit.WCPasteboard