When I try to draw with canvas where the canvas element has a large height and width (somewhere in the five digits but I haven't found exactly) it doesn't seem to work:
<canvas id="canvasElement" height="15000" width="15000"></canvas>
http://jsfiddle.net/mrxxzqqr/1/
Whereas with a canvas of 10000 width and 10000 height it works (at least in Chrome):
<canvas id="canvasElement" height="10000" width="10000"></canvas>
No errors, so I'm not sure why.