Don't do a pointless << 0.

Don't do a pointless << 0.

It's very common (universal?) that alpha is the top byte.
You'd hope the compiler would remove the left shift then,
but I've seen Clang just do a dumb left shift of zero. :(

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/8d029a4ebeda9d99c40b864e9c93c55be58b05af

[mtklein, 2015-01-25 16:30:31]

mtklein@google.com changed reviewers:
+ mtklein@google.com, reed@google.com

[mtklein, 2015-01-25 16:30:34]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-01-25 16:31:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/872243003/1

[commit-bot: I haz the power, 2015-01-25 16:31:38]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-01-25 22:31 UTC

[commit-bot: I haz the power, 2015-01-25 22:31:38]

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

[commit-bot: I haz the power, 2015-01-25 22:31:39]

No LGTM from a valid reviewer yet. Please ask for an LGTM from a
full Skia committer from
https://skia.googlesource.com/skia/+/master/CQ_COMMITTERS

[reed1, 2015-01-26 15:06:20]

The CQ bit was checked by reed@google.com

[reed1, 2015-01-26 15:06:20]

lgtm

[commit-bot: I haz the power, 2015-01-26 15:06:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/872243003/1

[commit-bot: I haz the power, 2015-01-26 15:07:06]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/8d029a4ebeda9d99c40b864e9c93c55be58b05af