Fixed the int to float conversion in ps_blend

webrender/res/clip_shared.glsl

@@ -28,7 +28,7 @@ CacheClipInstance fetch_clip_item(int index) {
     return cci;
 }
 
-// The transformed vertex function that always covers the whole whole clip area,
+// The transformed vertex function that always covers the whole clip area,
 // which is the intersection of all clip instances of a given primitive
 TransformVertexInfo write_clip_tile_vertex(vec4 local_clip_rect,
                                            Layer layer,

webrender/res/ps_blend.vs.glsl

@@ -40,7 +40,7 @@ void main(void) {
     vUv = vec3(mix(st0, st1, aPosition.xy), src.size_target_index.z);
 
     vOp = blend.src_id_target_id_op_amount.z;
-    vAmount = blend.src_id_target_id_op_amount.w / 65535.0;
+    vAmount = float(blend.src_id_target_id_op_amount.w) / 65535.0;
 
     gl_Position = uTransform * vec4(local_pos, blend.z, 1.0);
 }