Remove a cast again, after it was shown to worsen Windows perf.

Remove a cast again, after it was shown to worsen Windows perf.

This will hurt Linux x64 perf, but we think that's a compiler bug and we're
willing to take the hit for the better clarity of the code sans cast as well as
the better Windows perf.  Hopefully eventually the compiler will improve.

BUG=504813
TEST=none
TBR=andrew

Committed: https://crrev.com/3c60d614636a858e18fda9e52045fd1192517b8d
Cr-Commit-Position: refs/heads/master@{#9516}

[Peter Kasting, 2015-06-29 21:33:51]

pkasting@chromium.org changed reviewers:
+ andrew@webrtc.org

[Peter Kasting, 2015-06-29 21:34:09]

The CQ bit was checked by pkasting@chromium.org

[commit-bot: I haz the power, 2015-06-29 21:34:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1215053002/1

[commit-bot: I haz the power, 2015-06-29 22:16:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-29 22:16:55]

Patchset 1 (id:??) landed as
https://crrev.com/3c60d614636a858e18fda9e52045fd1192517b8d
Cr-Commit-Position: refs/heads/master@{#9516}

[Andrew MacDonald, 2015-06-29 22:52:13]

lgtm