Update WR.

- Subpixel positioning improvements.
- Clipping fixes and optimizations.
- Fix panic when transform can't be inverted.
- Support multiple filters on single stacking context.
- Optimize gradients, support unlimited stops.
- Add external image + texture cache support.
- Support error path on shader compile error.
- Optimize border handling in texture atlas.
- Preliminary work towards clip/scroll root changes.

components/layout/webrender_helpers.rs

@@ -229,8 +229,8 @@ impl WebRenderDisplayItemConverter for DisplayItem {
                             let glyph_offset = glyph.offset().unwrap_or(Point2D::zero());
                             let glyph = webrender_traits::GlyphInstance {
                                 index: glyph.id(),
-                                x: (origin.x + glyph_offset.x).to_f32_px(),
-                                y: (origin.y + glyph_offset.y).to_f32_px(),
+                                point: Point2D::new((origin.x + glyph_offset.x).to_f32_px(),
+                                                    (origin.y + glyph_offset.y).to_f32_px()),
                             };
                             glyphs.push(glyph);
                         }
@@ -354,7 +354,11 @@ impl WebRenderDisplayItemConverter for DisplayItem {
             }
             DisplayItem::PopStackingContext(_) => builder.pop_stacking_context(),
             DisplayItem::PushScrollRoot(ref item) => {
-                builder.push_scroll_layer(item.scroll_root.clip.to_rectf(),
+                let clip = builder.new_clip_region(&item.scroll_root.clip.to_rectf(),
+                                                   vec![],
+                                                   None);
+
+                builder.push_scroll_layer(clip,
                                           item.scroll_root.size.to_sizef(),
                                           item.scroll_root.id.convert_to_webrender());
             }