gpu: Port gles2_implementation_no_check target to GN.

gpu: Port gles2_implementation_no_check target to GN.

It is necessary because gles2_conform_supports depends on it and will
port it later.

Tested on Linux with the following command lines:

$ gn gen out-gn
$ ninja -C out-gn gles2_implementation_no_check

BUG=None
TEST=see above
R=jbauman@chromium.org,dpranke@chromium.org
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Committed: https://crrev.com/df41605a0de6646b7288a10408f6ea768c312cd8
Cr-Commit-Position: refs/heads/master@{#318869}

[Dirk Pranke, 2015-03-01 20:29:28]

LGTM. 

Make sure you specify 

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

in the CL description so that the CQ picks up all of the GN bots.

[tfarina, 2015-03-02 23:36:25]

jbauman, I need your approval for gpu/command_buffer.

[jbauman, 2015-03-03 00:01:44]

lgtm

[tfarina, 2015-03-03 12:47:35]

The CQ bit was checked by tfarina@chromium.org

[commit-bot: I haz the power, 2015-03-03 12:48:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/969603002/1

[commit-bot: I haz the power, 2015-03-03 14:11:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-03 14:12:18]

Patchset 1 (id:??) landed as
https://crrev.com/df41605a0de6646b7288a10408f6ea768c312cd8
Cr-Commit-Position: refs/heads/master@{#318869}