Incorrect rendering on Safari 6

```
What steps will reproduce the problem?
1. View any JSC3D example in Safari 6 on Mac OS X 10.7 or 10.8.

What is the expected output? What do you see instead?
- The geometry looks very blocky compared to other browsers (including earlier
versions of Safari).

What version of the product are you using? On what operating system?
- Latest source code. Mac OS X 10.7.4. Safari 6.0. (I am advised that the same
problem occurs in Mac OS X 10.8.)

Please provide any additional information below.

- This may be related to some changes to how Safari 6 handles the Canvas
element? If so, here is some info:

* http://www.html5rocks.com/en/tutorials/canvas/hidpi/
* http://www.phoboslab.org/log/2012/09/drawing-pixels-is-hard
* http://www.youtube.com/watch?v=_YvlaK3FvDA

- These changes apparently relate to Apple's new "retina display" devices, but
my Mac is an old MacBook without a retina display.
```

Original issue reported on code.google.com by `bgsaw...@iinet.net.au` on 29 Sep 2012 at 2:10