Sync changes from mozilla-central gfx/wr

webrender/res/brush_conic_gradient.glsl

@@ -114,8 +114,8 @@ Fragment conic_gradient_brush_fs() {
 #endif
 
     vec2 current_dir = pos - V_CENTER;
-    float current_angle = atan(current_dir.y, current_dir.x) + (PI / 2 - V_ANGLE);
-    float offset = mod(current_angle / (2 * PI), 1.0);
+    float current_angle = atan(current_dir.y, current_dir.x) + (PI / 2.0 - V_ANGLE);
+    float offset = mod(current_angle / (2.0 * PI), 1.0);
 
     vec4 color = sample_gradient(V_GRADIENT_ADDRESS,
                                  offset,

webrender/tests/angle_shader_validation.rs

@@ -105,6 +105,10 @@ const SHADERS: &[Shader] = &[
         name: "brush_mix_blend",
         features: BRUSH_FEATURES,
     },
+    Shader {
+        name: "brush_conic_gradient",
+        features: GRADIENT_FEATURES,
+    },
     Shader {
         name: "brush_radial_gradient",
         features: GRADIENT_FEATURES,