Use real time instead of fixed time steps

src/main.ts

@@ -138,10 +138,10 @@ var lastTime = new Date().getTime();
 var counter = 0.0;
 var fps = 0;
 function drawScene(buffer: WebGLBuffer, program: WebGLProgram) {
-    timeSpent += 1.0 / 60.0;
     fps++;
     let now = new Date();
     let delta = now.getTime() - lastTime;
+    timeSpent += delta;
     if ((counter += delta) >= 1000.) {
         counter = 0;
         console.log("FPS: " + fps);