Always write data to new buffer in SimulateAttrib0

This is to work around linux nvidia driver bug.

TEST=asan
BUG=118970


Review URL: http://codereview.chromium.org/10019003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@131538 0039d316-1c4b-4281-b951-d872f2087c98
void GLES2DecoderImpl::DoClear(GLbitfield mask) {
  if (CheckBoundFramebuffersValid("glClear")) {
    UNSHIPPED_TRACE_EVENT_INSTANT2("test_gpu", "DoClear", "red", clear_red_,
                                   "green", clear_green_);
    ApplyDirtyState();
    glClear(mask);
  }
}

void GLES2DecoderImpl::DoClear(GLbitfield mask) {
  if (CheckBoundFramebuffersValid("glClear")) {
    UNSHIPPED_TRACE_EVENT_INSTANT2("test_gpu", "DoClear", "red", clear_red_,
                                   "green", clear_green_);
    ApplyDirtyState();
    glClear(mask);
  }
}
