NEWT WindowImpl: Don't waitForPosition(..) if child window - issues w/ different toolkits!

With Applet3 plugin (firefox - using GTK), our child window seems to receives the absolute position,
or 'arbitrary' values (?).
Will need to figure out how to properly determine these cases.

In the meantime, simply turn off waitForPosition(..) for child windows,
which shall not harm NEWT.

Impacts following actions as child window:
- createNativeWindow
- reparent
- fullscreen
JOGLNewtApplet3Run: Don't set position if normal child window.