Bug 1589402 - Stop rounding complex clip rects in layout space. r=jrmuizel

We already snap the complex clip rects during scene building, taking
into account any necessary transforms and device pixel scaling. Just
like normal clips, we shouldn't round in layout space.

Differential Revision: https://phabricator.services.mozilla.com/D52673

--HG--
extra : moz-landing-system : lando

gfx/webrender_bindings/WebRenderTypes.h

@@ -604,7 +604,7 @@ static inline wr::BorderRadius ToBorderRadius(
 static inline wr::ComplexClipRegion ToComplexClipRegion(
     const nsRect& aRect, const nscoord* aRadii, int32_t aAppUnitsPerDevPixel) {
   wr::ComplexClipRegion ret;
-  ret.rect = ToRoundedLayoutRect(
+  ret.rect = ToLayoutRect(
       LayoutDeviceRect::FromAppUnits(aRect, aAppUnitsPerDevPixel));
   ret.radii = ToBorderRadius(
       LayoutDeviceSize::FromAppUnits(