Let it snow: minified browser URL edition

javascript:!function n(){function t(n){n.id=h.toString(16),h++,u[n.id]=n}function e(n){delete u[n.id]}function i(){function n(n){return Math.random()*n}function i(t){return Math.floor(n(t))}var r=i(o),c=-10,u=n(5),h={x:n(1)<.5?n(2):-1*n(2),y:u};this.run=function(){r+=h.x,c+=h.y,a.beginPath(),a.fillStyle="#ccc",a.arc(r,c,u,2*Math.PI,!1),a.fill(),a.closePath(),(0>r||r>o||c>d)&&e(this)},t(this)}var o,d,r=document.createElement("canvas"),c=document.createElement("style");if(!document.body)return n(),!1;c.innerHTML="*{margin:0;padding:0;}canvas{position:fixed;left:0;top:0;z-index:100;}",document.body.appendChild(r),document.body.appendChild(c);var a=r.getContext("2d"),u={},h=0;!function f(){new i,setTimeout(f,0)}(),function l(){(o!=window.innerWidth||d!=window.innerHeight)&&(r.width=o=window.innerWidth,r.height=d=window.innerHeight),a.clearRect(0,0,o,d);for(var n in u)u[n]&&u[n].run();setTimeout(l,1e3/60)}()}();void(0);

// 1. Paste this into the URL above (the address bar).
// 2. Make sure the "javascript:" at the beginning survives the copy/paste.
// 3. Hit enter.
// 4. Enjoy snow.

// Source: https://jsfiddle.net/B1KMusic/TNBYN/

// Improved version: http://pastebin.com/haPy6bSb