A number of compositing/ DRT tests fail.
These tests are executed in MacOS runs only.
Most of these test (but compositing/framesets/composited-frame-alignment.html) were not present in DRT workspace before Webkit merge.
Tests fail with 8u102, 8u112 and 9.
Half of the tests time out with 8u102.
Test compositing/framesets/composited-frame-alignment.html fails; other tests seem to just not work.

Affected tests:
compositing/animation/animation-backing.html
compositing/backing/backface-visibility-flip.html
compositing/backing/backface-visibility-in-3dtransformed.html
compositing/backing/border-radius-no-backing.html
compositing/backing/child-layer-no-backing.html
compositing/backing/filter-no-backing.html
compositing/backing/form-controls-backing.html
compositing/backing/inline-block-no-backing.html
compositing/backing/masked-child-no-backing.html
compositing/backing/no-backing-for-opacity-0-child.html
compositing/backing/replaced-child-no-backing.html
compositing/backing/toggle-opacity-0-child.html
compositing/backing/whitespace-nodes-no-backing.html
compositing/clipping/border-radius-overflow-hidden-stacking-context.html
compositing/contents-opaque/opaque-with-scrolled.html
compositing/contents-scale/rounded-contents-scale.html
compositing/fixed-positioned-pseudo-content-no-compositing.html
compositing/fixed-with-fixed-layout.html
compositing/framesets/composited-frame-alignment.html
compositing/geometry/fixed-transformed.html
compositing/iframes/display-none-subframe.html
compositing/layer-creation/fixed-overlap-extent-rtl.html
compositing/layer-creation/fixed-overlap-extent.html
compositing/layer-creation/mismatched-rotated-transform-animation-overlap.html
compositing/layer-creation/mismatched-rotated-transform-transition-overlap.html
compositing/layer-creation/mismatched-transform-transition-overlap.html
compositing/layer-creation/multiple-keyframes-animation-overlap.html
compositing/layer-creation/scale-rotation-animation-overlap.html
compositing/layer-creation/scale-rotation-transition-overlap.html
compositing/layer-creation/subpixel-adjacent-layers-overlap.html
compositing/layer-creation/translate-animation-overlap.html
compositing/layer-creation/translate-scale-animation-overlap.html
compositing/layer-creation/translate-scale-transition-overlap.html
compositing/layer-creation/translate-transition-overlap.html
compositing/layer-creation/zoomed-clip-intersection.html
compositing/masks/compositing-clip-path-change-no-repaint.html
compositing/media-controls-bar-appearance-big.html
compositing/media-controls-bar-appearance.html
compositing/repaint/iframes/composited-iframe-with-fixed-background-doc-repaint.html
compositing/repaint/iframes/compositing-iframe-scroll-repaint.html
compositing/repaint/iframes/compositing-iframe-with-fixed-background-doc-repaint.html
compositing/scrolling/touch-scroll-to-clip.html
compositing/tiling/transform-origin-tiled.html
compositing/updates/no-style-change-updates.html
compositing/visible-rect/backing-change-height-from-zero.html
compositing/visible-rect/coverage-clipped.html
compositing/visible-rect/coverage-scrolling.html
compositing/visible-rect/iframe-with-layers-outside-viewport.html
compositing/visible-rect/mask-layer-coverage.html