FramebufferTest: Fix InvalidateIncompleteDepthStencil

The test FramebufferTest_ES3.InvalidateIncompleteDepthStencil is
currently calling glFramebufferTextureLayer() with the parameter
level = 2. However, the texture was created with only 2 levels, so the
glFramebufferTextureLayer() call is returning GL_INVALID_VALUE when an
OpenGL ES 3.2 context is being tested:

OpenGL ES 3.2 Spec
> ## 9.2. BINDING AND MANAGING FRAMEBUFFER OBJECTS
> level specifies the mipmap level of the texture image to be attached
> to the framebuffer, and must satisfy the following conditions:
> • If texture refers to an immutable-format texture, level must be
> greater than or equal to zero and smaller than the value of
> TEXTURE_IMMUTABLE_LEVELS for texture.

The test passes when the "built-in" ANGLE is tested with the GN arg
`angle_test_enable_system_egl = false` (default), because a GLES 3.0
context can be forced. However, it fails when the device's drivers are
tested with `angle_test_enable_system_egl = true`, where the device
returns the highest supported GLES context version (3.2) because the
validation being restricted to GLES 3.1+.

Fix the test by updating the call to glFramebufferTextureLayer() to use
level = 1, which still results in an incomplete framebuffer.

Bug: b/514390133
Test: angle_end2end_tests \
  --gtest_filter=FramebufferTest_ES3.InvalidateIncompleteDepthStencil*
Change-Id: Idaa38e7ec975bb1cb4254a7363d8e950d1d94b10
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/7881712
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>

src/tests/gl_tests/FramebufferTest.cpp

diff --git a/src/tests/gl_tests/FramebufferTest.cpp b/src/tests/gl_tests/FramebufferTest.cpp
index cc92e28..c5daf5e 100644
--- a/src/tests/gl_tests/FramebufferTest.cpp
+++ b/src/tests/gl_tests/FramebufferTest.cpp
@@ -620,9 +620,9 @@
     GLFramebuffer framebuffer;
     glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
 
-    // Try to attach level 2 (out of range) to GL_DEPTH_STENCIL_ATTACHMENT.
+    // Try to attach level 1 (out of range) to GL_DEPTH_STENCIL_ATTACHMENT.
     // This makes the framebuffer incomplete.
-    glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, texture, 2, 0);
+    glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, texture, 1, 0);
     EXPECT_GL_NO_ERROR();
 
     // Verify the framebuffer is incomplete.