Now that we draw pictures by using their local rect as a normal

primitive, we also need to apply clip masks to them, when they
are required.

For example, a picture may have a transform on it, and when it
gets drawn it needs to sample from a clip mask in this case since
the coordinate systems are not equal and the local clip rect
can not be applied in this case.

This fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1439059.

webrender/src/prim_store.rs

@@ -1722,8 +1722,8 @@ impl PrimitiveStore {
                 }
 
                 let (draw_text_transformed, original_reference_frame_id) = match pic.kind {
-                    PictureKind::Image { reference_frame_id, .. } => {
-                        may_need_clip_mask = false;
+                    PictureKind::Image { reference_frame_id, composite_mode, .. } => {
+                        may_need_clip_mask = composite_mode.is_some();
                         (true, Some(reference_frame_id))
                     }
                     PictureKind::BoxShadow { .. } |

wrench/reftests/transforms/nested-preserve-3d.yaml

@@ -0,0 +1,29 @@
+---
+root:
+  items:
+    -
+      bounds: [260, 260, 231, 231]
+      "clip-rect": [260, 260, 231, 231]
+      type: border
+      width: 3
+      "border-type": normal
+      color: 0 0 255 1.0000
+      style: dashed
+    -
+      bounds: [300, 300, 0, 0]
+      "clip-rect": [300, 300, 0, 0]
+      type: "stacking-context"
+      transform: [1, 0, 0, 0, 0, 0, 1, 0, 0, -1, 0, 0, 0, 75, -75, 1]
+      transform-style: preserve-3d
+      items:
+        -
+          type: "stacking-context"
+          transform: [1, 0, 0, 0, 0, 0.8660254, -0.5, 0, 0, 0.5, 0.8660254, 0, 0, 10.048096, 37.5, 1]
+          transform-style: preserve-3d
+          items:
+            -
+              bounds: [0, 0, 150, 150]
+              "clip-rect": [0, 0, 150, 150]
+              "clip-and-scroll": 0
+              type: rect
+              color: 255 255 0 0.4000

wrench/reftests/transforms/nested-rotate-x.yaml

@@ -0,0 +1,27 @@
+---
+root:
+  items:
+    -
+      bounds: [260, 260, 231, 231]
+      "clip-rect": [260, 260, 231, 231]
+      type: border
+      width: 3
+      "border-type": normal
+      color: 0 0 255 1.0000
+      style: dashed
+    -
+      bounds: [300, 300, 0, 0]
+      "clip-rect": [300, 300, 0, 0]
+      type: "stacking-context"
+      transform: [1, 0, 0, 0, 0, 0, 1, 0, 0, -1, 0, 0, 0, 75, -75, 1]
+      items:
+        -
+          type: "stacking-context"
+          transform: [1, 0, 0, 0, 0, 0.8660254, -0.5, 0, 0, 0.5, 0.8660254, 0, 0, 10.048096, 37.5, 1]
+          items:
+            -
+              bounds: [0, 0, 150, 150]
+              "clip-rect": [0, 0, 150, 150]
+              "clip-and-scroll": 0
+              type: rect
+              color: 255 255 0 0.4000

wrench/reftests/transforms/reftest.list

@@ -14,3 +14,5 @@ fuzzy(1,11) == prim-suite.yaml prim-suite.png
 zoom(4) == border-zoom.yaml border-zoom.png
 fuzzy(1,520) == perspective-origin.yaml perspective-origin.png
 fuzzy(1,120) == screen-space-blit.yaml screen-space-blit.png
+== nested-rotate-x.yaml nested-rotate-x.png
+== nested-preserve-3d.yaml nested-preserve-3d.png