Make index parameters in Ranges method match the type returned by size()

Make index parameters in Ranges method match the type returned by size()

This changes the index parameters in start() and end() to size_t so that
they match what size() returns. This fixes some compiler warnings that
become errors on some of the Windows bots.

BUG=408338
Committed: https://crrev.com/23f694a6bbee081b607da240018edc7898719805
Cr-Commit-Position: refs/heads/master@{#293441}

[acolwell GONE FROM CHROMIUM, 2014-09-04 19:16:30]

acolwell@chromium.org changed reviewers:
+ scherkus@chromium.org

[scherkus (not reviewing), 2014-09-04 19:28:51]

lgtm

[acolwell GONE FROM CHROMIUM, 2014-09-04 19:30:05]

The CQ bit was checked by acolwell@chromium.org

[commit-bot: I haz the power, 2014-09-04 19:34:21]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/acolwell@chromium.org/539203002/1

[commit-bot: I haz the power, 2014-09-05 01:52:14]

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

[commit-bot: I haz the power, 2014-09-05 01:52:15]

Try jobs failed on following builders:
  mac_chromium_rel_swarming on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[acolwell GONE FROM CHROMIUM, 2014-09-05 01:55:29]

The CQ bit was checked by acolwell@chromium.org

[commit-bot: I haz the power, 2014-09-05 01:58:31]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/acolwell@chromium.org/539203002/1

[commit-bot: I haz the power, 2014-09-05 04:49:08]

Committed patchset #1 (id:1) as 0f857b035cdbbc85a6cc712e1502ccc7ae166b39

[commit-bot: I haz the power, 2014-09-10 03:36:52]

Patchset 1 (id:??) landed as
https://crrev.com/23f694a6bbee081b607da240018edc7898719805
Cr-Commit-Position: refs/heads/master@{#293441}