Remove tombstones from SkTHash.

* Switch to linear probing - this allows delete to rearrange elements to fill in empty slots
* NULL -> nullptr


Change-Id: I741c2f3bb2734bf638d0c0a78c6cc549f563a5d9
Reviewed-on: https://skia-review.googlesource.com/5980
Commit-Queue: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
1 file changed