Validate glClearBuffer*v function |buffer| param on the client side

Otherwise we could read out-of-bounds even if an invalid |buffer| is passed
in and in theory we should not read the buffer at all.

BUG=908749
TEST=gl_tests in ASAN build
R=piman@chromium.org

Change-Id: I94b69b56ce3358ff9bfc0e21f0618aec4371d1ec
Reviewed-on: https://chromium-review.googlesource.com/c/1354571
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612023}
void GLClearFramebufferTest::SetDrawColor(GLfloat r,
                                          GLfloat g,
                                          GLfloat b,
                                          GLfloat a) {
  glUniform4f(color_handle_, r, g, b, a);
}

void GLClearFramebufferTest::SetDrawColor(GLfloat r,
                                          GLfloat g,
                                          GLfloat b,
                                          GLfloat a) {
  glUniform4f(color_handle_, r, g, b, a);
}
