8159690: [TESTBUG] Mark headful tests with @key headful.
Reviewed-by: simonis, alexsch

8150844: [hidpi] [macosx] -Dsun.java2d.uiScale should be taken into account for OS X
Reviewed-by: serb, avstepan

8150724: [TEST] HiDPI: create a test for multiresolution icons
Reviewed-by: alexsch, yan