ScreenFx: fix Std.string causing large string allocs on JS target

h3d/pass/ScreenFx.hx

@@ -15,7 +15,7 @@ class ScreenFx<T:h3d.shader.ScreenShader> {
 		this.shader = shader;
 		shaders = new hxsl.ShaderList(shader);
 		manager = new ShaderManager(output);
-		pass = new h3d.mat.Pass(Std.string(this), new hxsl.ShaderList(shader));
+		pass = new h3d.mat.Pass("screenfx", new hxsl.ShaderList(shader));
 		pass.culling = None;
 		pass.depth(false, Always);
 	}