Workaround Bug 910 (IcedTea-Web): NewtCanvasAWT shall postpone JAWTWindow destruction via explicit set flag.

IcedTea-Web_1.5pre+rbc73a1362e9c still issues NewtCanvasAWT.removeNotify()
before before Applet.destroy(), i.e. removes NewtCanvasAWT from the Container
ahead of time (Applet protocol destroy()).

However, it fixes the non AWT-EDT issue, i.e. calls NewtCanvasAWT.removeNotify()
from the actual AWT-EDT - good.

Since the root cause still exist, we cannot use heuristics as described in
Bug 910 comment 9, but need to set a flag in NewtCanvasAWT to skip JAWT destruction
and remove it latter within Applet.destroy().

NewtCanvasAWT.removeNotify.0 - isApplet true @ [AWT-EventQueue-0, isAWT-EDT true]