Bug 1520851 - Make a reference frame's transform not optional. r=kvark

No good reason for it to be an option.

Differential Revision: https://phabricator.services.mozilla.com/D16876

gfx/webrender_bindings/src/bindings.rs

@@ -1958,13 +1958,12 @@ pub extern "C" fn wr_dp_push_stacking_context(
     let mut wr_spatial_id = spatial_id.to_webrender(state.pipeline_id);
     let wr_clip_id = clip.to_webrender(state.pipeline_id);
 
-    let is_reference_frame = transform_binding.is_some();
     // Note: 0 has special meaning in WR land, standing for ROOT_REFERENCE_FRAME.
     // However, it is never returned by `push_reference_frame`, and we need to return
     // an option here across FFI, so we take that 0 value for the None semantics.
     // This is resolved into proper `Maybe<WrSpatialId>` inside `WebRenderAPI::PushStackingContext`.
     let mut result = WrSpatialId { id: 0 };
-    if is_reference_frame {
+    if let Some(transform_binding) = transform_binding {
         wr_spatial_id = state.frame_builder.dl_builder.push_reference_frame(
             &bounds,
             wr_spatial_id,

gfx/wr/webrender/src/clip_scroll_tree.rs

@@ -352,7 +352,7 @@ impl ClipScrollTree {
         &mut self,
         parent_index: Option<SpatialNodeIndex>,
         transform_style: TransformStyle,
-        source_transform: Option<PropertyBinding<LayoutTransform>>,
+        source_transform: PropertyBinding<LayoutTransform>,
         kind: ReferenceFrameKind,
         origin_in_parent_reference_frame: LayoutVector2D,
         pipeline_id: PipelineId,

gfx/wr/webrender/src/display_list_flattener.rs

@@ -690,7 +690,7 @@ impl<'a> DisplayListFlattener<'a> {
             Some(spatial_node_index),
             iframe_pipeline_id,
             TransformStyle::Flat,
-            None,
+            PropertyBinding::Value(LayoutTransform::identity()),
             ReferenceFrameKind::Transform,
             origin,
         );
@@ -1584,7 +1584,7 @@ impl<'a> DisplayListFlattener<'a> {
         parent_index: Option<SpatialNodeIndex>,
         pipeline_id: PipelineId,
         transform_style: TransformStyle,
-        source_transform: Option<PropertyBinding<LayoutTransform>>,
+        source_transform: PropertyBinding<LayoutTransform>,
         kind: ReferenceFrameKind,
         origin_in_parent_reference_frame: LayoutVector2D,
     ) -> SpatialNodeIndex {
@@ -1619,7 +1619,7 @@ impl<'a> DisplayListFlattener<'a> {
             None,
             pipeline_id,
             TransformStyle::Flat,
-            None,
+            PropertyBinding::Value(LayoutTransform::identity()),
             ReferenceFrameKind::Transform,
             LayoutVector2D::zero(),
         );

gfx/wr/webrender/src/spatial_node.rs

@@ -116,15 +116,14 @@ impl SpatialNode {
     pub fn new_reference_frame(
         parent_index: Option<SpatialNodeIndex>,
         transform_style: TransformStyle,
-        source_transform: Option<PropertyBinding<LayoutTransform>>,
+        source_transform: PropertyBinding<LayoutTransform>,
         kind: ReferenceFrameKind,
         origin_in_parent_reference_frame: LayoutVector2D,
         pipeline_id: PipelineId,
     ) -> Self {
-        let identity = LayoutTransform::identity();
         let info = ReferenceFrameInfo {
             transform_style,
-            source_transform: source_transform.unwrap_or(PropertyBinding::Value(identity)),
+            source_transform,
             kind,
             origin_in_parent_reference_frame,
             invertible: true,

gfx/wr/webrender_api/src/display_item.rs

@@ -537,7 +537,7 @@ pub struct ReferenceFrame {
     pub transform_style: TransformStyle,
     /// The transform matrix, either the perspective matrix or the transform
     /// matrix.
-    pub transform: Option<PropertyBinding<LayoutTransform>>,
+    pub transform: PropertyBinding<LayoutTransform>,
     pub id: SpatialId,
 }
 

gfx/wr/webrender_api/src/display_list.rs

@@ -1256,7 +1256,7 @@ impl DisplayListBuilder {
         rect: &LayoutRect,
         parent: SpatialId,
         transform_style: TransformStyle,
-        transform: Option<PropertyBinding<LayoutTransform>>,
+        transform: PropertyBinding<LayoutTransform>,
         kind: ReferenceFrameKind,
     ) -> SpatialId {
         let id = self.generate_spatial_index();