remove RenderTargetFlags -- NewRenderTargetDirect will never clear

remove RenderTargetFlags -- NewRenderTargetDirect will never clear

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/65b48952d7253faf44feb91dfe8953295b1600d0

[reed2, 2014-09-19 00:25:58]

reed@chromium.org changed reviewers:
+ bsalomon@google.com, robertphillips@google.com

[reed2, 2014-09-19 00:25:59]

one caller in resource_provider.cc

[reed2, 2014-09-19 00:26:09]

The CQ bit was checked by reed@chromium.org

[commit-bot: I haz the power, 2014-09-19 00:26:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/583043002/1

[commit-bot: I haz the power, 2014-09-19 00:26:21]

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 a valid reviewer till 2014-09-19 06:26 UTC

[commit-bot: I haz the power, 2014-09-19 05:54:07]

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 a valid reviewer till 2014-09-19 11:54 UTC

[commit-bot: I haz the power, 2014-09-19 08:00:33]

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 a valid reviewer till 2014-09-19 14:00 UTC

[robertphillips, 2014-09-19 12:55:19]

lgtm

[commit-bot: I haz the power, 2014-09-19 12:56:34]

Committed patchset #1 (id:1) as 65b48952d7253faf44feb91dfe8953295b1600d0