Initial QuadTree implementation

In an effort to find a faster bounding box hierarchy than the R-Tree, a QuadTree has been implemented here.
For now, the QuadTree construction is generally faster than the R-Tree and the queries are a bit slower, so overall, SKP local tests showed QuadTree performance similar to the R-Tree performance.

Tests and bench are included in this cl.

At this point, I'd like to be able to commit this in order to more easily use the bots to test multiple configurations and a larger number of SKPs. The R-Tree BBH is still used by default so this change shouldn't affect chromium.

BUG=skia:
R=junov@chromium.org, junov@google.com, senorblanco@google.com, senorblanco@chromium.org, reed@google.com, sugoi@google.com, fmalita@google.com

Author: sugoi@chromium.org

Review URL: https://codereview.chromium.org/131343011

git-svn-id: http://skia.googlecode.com/svn/trunk@13282 2bbb7eff-a529-9590-31e7-b0007b416f81
16 files changed