renderer: Fix border profiling.

Was broken by #3011.

Also while at it, avoid setting and unsetting blend modes unnecessarily.

webrender/src/renderer.rs

@@ -3399,46 +3399,42 @@ impl Renderer {
 
         // Draw any borders for this target.
         if !target.border_segments_solid.is_empty() ||
-           !target.border_segments_complex.is_empty() {
+           !target.border_segments_complex.is_empty()
+        {
             let _timer = self.gpu_profile.start_timer(GPU_TAG_CACHE_BORDER);
-        }
 
-        if !target.border_segments_solid.is_empty() {
             self.set_blend(true, FramebufferKind::Other);
             self.set_blend_mode_premultiplied_alpha(FramebufferKind::Other);
 
-            self.shaders.cs_border_solid.bind(
-                &mut self.device,
-                &projection,
-                &mut self.renderer_errors,
-            );
-
-            self.draw_instanced_batch(
-                &target.border_segments_solid,
-                VertexArrayKind::Border,
-                &BatchTextures::no_texture(),
-                stats,
-            );
-
-            self.set_blend(false, FramebufferKind::Other);
-        }
+            if !target.border_segments_solid.is_empty() {
+                self.shaders.cs_border_solid.bind(
+                    &mut self.device,
+                    &projection,
+                    &mut self.renderer_errors,
+                );
 
-        if !target.border_segments_complex.is_empty() {
-            self.set_blend(true, FramebufferKind::Other);
-            self.set_blend_mode_premultiplied_alpha(FramebufferKind::Other);
+                self.draw_instanced_batch(
+                    &target.border_segments_solid,
+                    VertexArrayKind::Border,
+                    &BatchTextures::no_texture(),
+                    stats,
+                );
+            }
 
-            self.shaders.cs_border_segment.bind(
-                &mut self.device,
-                &projection,
-                &mut self.renderer_errors,
-            );
+            if !target.border_segments_complex.is_empty() {
+                self.shaders.cs_border_segment.bind(
+                    &mut self.device,
+                    &projection,
+                    &mut self.renderer_errors,
+                );
 
-            self.draw_instanced_batch(
-                &target.border_segments_complex,
-                VertexArrayKind::Border,
-                &BatchTextures::no_texture(),
-                stats,
-            );
+                self.draw_instanced_batch(
+                    &target.border_segments_complex,
+                    VertexArrayKind::Border,
+                    &BatchTextures::no_texture(),
+                    stats,
+                );
+            }
 
             self.set_blend(false, FramebufferKind::Other);
         }