Remove unused InstCounterClass.

Remove unused InstCounterClass.

This was added with r4719 (f7943035) to support testing
SkTRefArray. With 703d3c70 SkTRefArray and the associated test was
removed, but the supporting InstCounterClass was not.

Committed: https://skia.googlesource.com/skia/+/693e9930571929cbdc83f1e678b151a768c1bad8

[bungeman-skia, 2015-04-08 14:51:04]

bungeman@google.com changed reviewers:
+ mtklein@google.com

[bungeman-skia, 2015-04-08 14:51:04]

Some dead code left over from https://codereview.chromium.org/719113004 that I
just stumbled upon.

[bungeman-skia, 2015-04-08 14:51:09]

The CQ bit was checked by bungeman@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-08 14:51:15]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1063403003/1

[commit-bot: I haz the power, 2015-04-08 15:04:11]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-08 15:04:12]

This issue passed the CQ dry run.

[mtklein, 2015-04-08 15:06:12]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-04-08 15:06:12]

lgtm

[commit-bot: I haz the power, 2015-04-08 15:06:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1063403003/1

[commit-bot: I haz the power, 2015-04-08 15:06:29]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/693e9930571929cbdc83f1e678b151a768c1bad8