Framebuffer clear() needs to consider the situation some draw buffers are disabled.

This is when we expose DrawBuffers extension.

BUG=376951
TEST=the attached test case, webgl conformance
R=kbr@chromium.org,bajones@chromium.org

Review URL: https://codereview.chromium.org/315283002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@275338 0039d316-1c4b-4281-b951-d872f2087c98
bool GLES2DecoderImpl::CreateProgramHelper(GLuint client_id) {
  if (GetProgram(client_id)) {
    return false;
  }
  GLuint service_id = glCreateProgram();
  if (service_id != 0) {
    CreateProgram(client_id, service_id);
  }
  return true;
}

bool GLES2DecoderImpl::CreateProgramHelper(GLuint client_id) {
  if (GetProgram(client_id)) {
    return false;
  }
  GLuint service_id = glCreateProgram();
  if (service_id != 0) {
    CreateProgram(client_id, service_id);
  }
  return true;
}
