This allows to use builder.image(SWT.ICON_QUESTION) instead of
builder.image(getShell().getDisplay().getSystemImage(SWT.ICON_QUESTION));

Change-Id: Id084b226cdff70288db4d66f8688c4b88cabe243
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.ui/+/182104
Tested-by: Platform Bot <platform-bot@eclipse.org>
Reviewed-by: Marcus Höpfner <marcus.hoepfner@sap.com>