DEPS: Remove obsolete reference to "native_client/src/third_party/ppapi"

DEPS: Remove obsolete reference to "native_client/src/third_party/ppapi"

This directory hasn't been checked out by DEPS for a long time.  There
is no need for the "ios" section to override it to prevent this
directory being checked out.

BUG=none
TEST=none

Committed: https://crrev.com/480f9380b0ba5e2ef6b346ab88740711c0be0088
Cr-Commit-Position: refs/heads/master@{#293407}

[Mark Seaborn, 2014-09-04 19:24:02]

mseaborn@chromium.org changed reviewers:
+ dschuff@chromium.org

[Derek Schuff, 2014-09-04 19:34:18]

lgtm

[Mark Seaborn, 2014-09-04 21:12:39]

The CQ bit was checked by mseaborn@chromium.org

[commit-bot: I haz the power, 2014-09-04 21:14:13]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mseaborn@chromium.org/530143003/1

[commit-bot: I haz the power, 2014-09-05 02:31:48]

Committed patchset #1 (id:1) as 1beb1d2b043fe0d2937f9a70b29939459601eaa9

[commit-bot: I haz the power, 2014-09-10 03:35:47]

Patchset 1 (id:??) landed as
https://crrev.com/480f9380b0ba5e2ef6b346ab88740711c0be0088
Cr-Commit-Position: refs/heads/master@{#293407}