Bug 1505871. Don't borrow frame_state.surface for the duration of prepare_for_render. r=gw

We need to call update on the filter data handle which needs to use frame_state (in a later patch), so we can't borrow across that call.

gfx/wr/webrender/src/picture.rs

@@ -2888,7 +2888,6 @@ impl PicturePrimitive {
                 surface_info.device_pixel_scale,
             )
         };
-        let surfaces = &mut frame_state.surfaces;
 
         let (map_raster_to_world, map_pic_to_raster) = create_raster_mappers(
             prim_instance.spatial_node_index,
@@ -2988,7 +2987,7 @@ impl PicturePrimitive {
 
                 let render_task_id = frame_state.render_tasks.add(blur_render_task);
 
-                surfaces[surface_index.0].tasks.push(render_task_id);
+                frame_state.surfaces[surface_index.0].tasks.push(render_task_id);
 
                 PictureSurface::RenderTask(render_task_id)
             }
@@ -3046,7 +3045,7 @@ impl PicturePrimitive {
                 self.secondary_render_task_id = Some(picture_task_id);
 
                 let render_task_id = frame_state.render_tasks.add(blur_render_task);
-                surfaces[surface_index.0].tasks.push(render_task_id);
+                frame_state.surfaces[surface_index.0].tasks.push(render_task_id);
 
                 if let Some(mut request) = frame_state.gpu_cache.request(&mut self.extra_gpu_data_handle) {
                     // TODO(gw): This is very hacky code below! It stores an extra
@@ -3107,7 +3106,7 @@ impl PicturePrimitive {
                 );
 
                 let render_task_id = frame_state.render_tasks.add(picture_task);
-                surfaces[surface_index.0].tasks.push(render_task_id);
+                frame_state.surfaces[surface_index.0].tasks.push(render_task_id);
                 PictureSurface::RenderTask(render_task_id)
             }
             PictureCompositeMode::Puppet { .. } |
@@ -3140,12 +3139,12 @@ impl PicturePrimitive {
                 );
 
                 let render_task_id = frame_state.render_tasks.add(picture_task);
-                surfaces[surface_index.0].tasks.push(render_task_id);
+                frame_state.surfaces[surface_index.0].tasks.push(render_task_id);
                 PictureSurface::RenderTask(render_task_id)
             }
         };
 
-        surfaces[raster_config.surface_index.0].surface = Some(surface);
+        frame_state.surfaces[raster_config.surface_index.0].surface = Some(surface);
 
         true
     }