Minor performance improvements

[pjcozzi]

This is a minor change as I start to improve commands for models.

For the default view in the terrain Sandcastle example, the hotspot was creating the depth plane's typed array at 0.34% and the garbage collector also at 0.34%. This eliminates the typed array creation from the profile and drops the garbage collector to 0.18%.

[kring]

Were you able to get Web Mercator terrain to work in order to test the pole filling? I get an exception when I try.

Introduced with the geometry batching stuff? Or maybe it's been broken longer than that...

[mramato]

This worked recently, so I bet it broke with Geometry WebWorkers.

[mramato]

Okay, I just checked master and it works there.

[kring]

How did you test it? I hacked EllipsoidTerrainProvider to use WebMercatorTilingScheme instead of GeographicTilingScheme. I'll try in master, though it's not clear how Cozzi's changes would cause what I'm seeing.

[pjcozzi]

Were you able to get Web Mercator terrain to work in order to test the pole filling?

I didn't get any love when I tried.

[kring]

It doesn't work in master for me. @pjcozzi did you get the same problem?

[pjcozzi]

How did you test it? I hacked EllipsoidTerrainProvider to use WebMercatorTilingScheme instead of GeographicTilingScheme.

I tried this too, but I didn't get a globe at all, and it didn't hit the breakpoints in my new code.

Shame on me, I know.

[kring]

Ok well this pull request looks fine. Pole filling is totally broken, but that's a separate problem. I'll write an issue for it.