WebGLRenderer: Apply pixelRatio to Points size. See #7451.

src/renderers/WebGLRenderer.js

@@ -1869,7 +1869,7 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 		uniforms.psColor.value = material.color;
 		uniforms.opacity.value = material.opacity;
-		uniforms.size.value = material.size;
+		uniforms.size.value = material.size * pixelRatio;
 		uniforms.scale.value = _canvas.height / 2.0; // TODO: Cache this.
 
 		uniforms.map.value = material.map;