Just use one version of the scripts in both the browser and in SkV8.

experimental/SkV8Example/snow.js

+var IS_SKV8 = typeof document == "undefined";
+
+function circlePath(r) {
+  if (IS_SKV8) {
+    var p = new Path();
+    p.oval(0, 0, r, r);
+    p.closePath();
+    return p;
+  } else {
+    return null;
+  }
+}
+
+var onDraw = function() {
+  var W = 500;
+  var H = 500;
+  var NumParticles = 100;
+
+  var angle = 0;
+  var ticks = 0;
+  var particles =[];
+
+  for (var i = 0; i < NumParticles; i++) {
+    particles[i] = {
+      x:    Math.floor(Math.random()*W),
+      y:    Math.floor(Math.random()*H),
+      r:    Math.floor(Math.random()*7+1),
+      path: circlePath(Math.random()*7+1),
+    }
+  }
+
+  function draw(ctx) {
+    ctx.fillStyle = "#ADD8E6";
+    ctx.fillRect(0, 0, W-1, H-1);
+    ctx.fillStyle = "#FFFFFF";
+
+    angle += 0.0039;
+    for (var i = 0; i < particles.length; i++) {
+      var p = particles[i];
+      p.x += Math.floor(Math.sin(angle)*5.0);
+      p.y += 0.6*p.r;
+      if (p.x > W) {
+        p.x-=W;
+      }
+      if (p.x < 0) {
+        p.x += W;
+      }
+      if(p.y>(H+1)){
+        p.y = 0;
+      }
+      if (IS_SKV8) {
+        ctx.save();
+        ctx.translate(p.x, p.y);
+        ctx.fill(p.path);
+        ctx.restore();
+      } else {
+        ctx.beginPath();
+        ctx.moveTo(p.x, p.y);
+        ctx.arc(p.x, p.y, p.r, 0, 2*Math.PI, true);
+        ctx.closePath();
+        ctx.fill();
+      }
+    };
+
+    ticks++;
+    if (IS_SKV8) {
+      inval();
+    }
+  }
+
+  function fps() {
+    console.log(ticks);
+    ticks = 0;
+    setTimeout(fps, 1000);
+  }
+
+  setTimeout(fps, 1000);
+
+  return draw;
+}();
+
+if (!IS_SKV8) {
+  window.onload = function(){
+    var canvas = document.getElementById("snow");
+    var ctx = canvas.getContext("2d");
+    function drawCallback() {
+      onDraw(ctx);
+      setTimeout(drawCallback, 1);
+    }
+    setTimeout(drawCallback, 1);
+  }
+}