Auto merge of #1820 - glennw:xf-clip, r=kvark

Add a workaround for inner rects on transformed clips.

Fixes #1814.

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Author: bors-servo

webrender/src/render_task.rs

@@ -329,7 +329,10 @@ impl RenderTask {
                 }
 
                 match clip_info.bounds.inner {
-                    Some(ref inner) if !inner.device_rect.is_empty() => {
+                    // Inner rects aren't valid if the item is not axis-aligned, which can
+                    // be determined by the apply_rectangles field. This is mostly a band-aid
+                    // until we have better handling of inner rectangles for transformed clips.
+                    Some(ref inner) if !work_item.apply_rectangles && !inner.device_rect.is_empty() => {
                         inner_rect = inner_rect.and_then(|r| r.intersection(&inner.device_rect));
                         !inner.device_rect.contains_rect(&task_rect)
                     }

wrench/reftests/transforms/image-rotated-clip.png

@@ -0,0 +1,20 @@
+---
+root:
+  items:
+    -
+      bounds: [18, 18, 400, 400]
+      "clip-rect": [18, 18, 400, 400]
+      type: clip
+      id: 1
+      "content-size": [400, 400]
+    -
+      bounds: [0, 0, 0, 0]
+      "clip-and-scroll": 1
+      type: "stacking-context"
+      transform: [0.70710677, 0.70710677, 0, 0, -0.70710677, 0.70710677, 0, 0, 0, 0, 1, 0, 218, -64.84271, 0, 1]
+      items:
+        -
+          bounds: [0, 0, 400, 400]
+          "clip-rect": [0, 0, 400, 400]
+          "clip-and-scroll": 1
+          image: solid-color(255, 0, 0, 255, 400, 400)

wrench/reftests/transforms/image-rotated-clip.yaml

@@ -1,5 +1,6 @@
 == local-clip.yaml local-clip.png
 == rotated-clip.yaml rotated-clip.png
+== image-rotated-clip.yaml image-rotated-clip.png
 # Something leaks the state: the test passes if only run `reftest reftests/transform`
 # but fails when all the tests are run
 fuzzy(1,1) == rotated-image.yaml rotated-image.png