Bug 577993 - SWT disposed exception in DiffPainter

This change ensures no disposed exceptions are thrown by
DiffPainter.postRedraw(), in case an editor is closed before the
postRedraw() is finished.

Change-Id: I1d3b4804243814c6ce0e7d0f51efdaf093a34430
Signed-off-by: Simeon Andreev <simeon.danailov.andreev@gmail.com>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.text/+/189211
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Andrey Loskutov <loskutov@gmx.de>
1 file changed