Math.random is not very random

[stevemessick]

From anonymous editor feedback:

Math.random produces very bad results (very unrandom). Try doing a phase plot on a canvas (points of Xi,Xi-1) and you will see - not random.

 CanvasElement can = new CanvasElement(400, 400);
 document.body.elements.add(can);
 CanvasRenderingContext2D g = can.getContext("2d");
 g.canvas.style.border="solid 1px";
 double x = Math.random()400;
 double y = 0.0;
 for(int i=0;i<1000;++i) {
   g.beginPath();
   g.arc(x,y,2,0,Math.PI2,true);
   y = x;
   x = Math.random()*400;
   g.closePath();
   g.fill();
 }
////////////////////////////////////////////////////////////////////////////////////
Editor Version: 8124

[whesse]

Added Duplicate label.
Marked as being merged into #499.