Revert of gpu: support GL_TEXTURE_CUBE_MAP destination target to Copy(Sub)TextureCHROMIUM.

Revert of gpu: support GL_TEXTURE_CUBE_MAP destination target to Copy(Sub)TextureCHROMIUM. (patchset #10 id:200001 of https://codereview.chromium.org/1275773003/ )

Reason for revert:
Linux AMD GPU FYI bot has a broken gl_tests, likely because of this patch.

http://build.chromium.org/p/chromium.gpu.fyi/builders/Linux%20Release%20%28ATI%29/builds/41273

[ RUN      ] GLCopyTextureCHROMIUMTests/GLCopyTextureCHROMIUMTest.Basic/2
Received signal 11 SEGV_MAPERR 000000000045
#0 0x000000492795 base::debug::(anonymous namespace)::StackDumpSignalHandler()
#1 0x7ff52630acb0 <unknown>
#2 0x7ff5232a858c <unknown>
#3 0x7ff5230a247c <unknown>
#4 0x7ff5230a33ae <unknown>
#5 0x7ff5227e8585 <unknown>
#6 0x7ff5227e9b0a <unknown>
#7 0x7ff522bf75c3 <unknown>
#8 0x0000004f7ba4 gfx::GLApiBase::glCopyTexImage2DFn()
#9 0x000000596ac1 (anonymous namespace)::DoCopyTexImage2D()
#10 0x0000005968c4 gpu::CopyTextureCHROMIUMResourceManager::DoCopyTexture()

Original issue's description:
> gpu: support GL_TEXTURE_CUBE_MAP destination target to Copy(Sub)TextureCHROMIUM.
>
> It makes it possible to optimize WebGL.
>
> TEST=gl_tests GLCopyTextureCHROMIUMTests/GLCopyTextureCHROMIUMTest.*
> BUG=517548
>
> Committed: https://crrev.com/fa25f0e5786527e63c6ff9aeda77da3bd7456ee3
> Cr-Commit-Position: refs/heads/master@{#347354}

TBR=piman@chromium.org,sievers@chromium.org,kbr@chromium.org,zmo@chromium.org,dongseong.hwang@intel.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=517548, 528374
Committed: https://crrev.com/8ff8391503975e2559bf14e544b6aa469f612d25
Cr-Commit-Position: refs/heads/master@{#347465}

[Jamie Madill, 2015-09-04 18:27:58]

Created Revert of gpu: support GL_TEXTURE_CUBE_MAP destination target to
Copy(Sub)TextureCHROMIUM.

[commit-bot: I haz the power, 2015-09-04 18:28:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1304103005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1304103005/1

[commit-bot: I haz the power, 2015-09-04 18:29:11]

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

[commit-bot: I haz the power, 2015-09-04 18:29:12]

Failed to commit the patch.

[commit-bot: I haz the power, 2015-09-04 18:30:00]

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

[Jamie Madill, 2015-09-04 19:07:30]

The CQ bit was checked by jmadill@chromium.org

[commit-bot: I haz the power, 2015-09-04 19:07:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1304103005/200001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1304103005/200001

[commit-bot: I haz the power, 2015-09-04 19:08:49]

Committed patchset #2 (id:200001)

[commit-bot: I haz the power, 2015-09-04 19:09:45]

Patchset 2 (id:??) landed as
https://crrev.com/8ff8391503975e2559bf14e544b6aa469f612d25
Cr-Commit-Position: refs/heads/master@{#347465}

[dshwang, 2015-09-28 11:14:53]

On 2015/09/04 19:09:45, commit-bot: I haz the power wrote:
> Patchset 2 (id:??) landed as
> https://crrev.com/8ff8391503975e2559bf14e544b6aa469f612d25
> Cr-Commit-Position: refs/heads/master@{#347465}

thx for reverting. Let me re-land with ATI handling.