Revert "Reuse the canvas element when plot is called"
Revert "Reuse the canvas element when plot is called"

2/2 removing reuse canvas patches.

The main reason for this is that in profiling vs the current SVN
code, I can't really see any improvement one way or the other, so
I will prefer the SVN version.

This reverts commit 6d20287d3a82967aab0524e1a9e602802f103d27.

ryleyb/Flot-Graphs