dawn: Enable OpenGLBackend for ComputeLayoutMemoryBufferTests

The layout issues should now be fixed with the Std140 transform.

Bug: dawn:942
Change-Id: I714c2edb39f27b39f66c1e913f22232ad7908896
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/103000
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Auto-Submit: Ben Clayton <bclayton@google.com>

src/dawn/tests/end2end/ComputeLayoutMemoryBufferTests.cpp

@@ -347,11 +347,7 @@ auto GenerateParams() {
             D3D12Backend(),
             MetalBackend(),
             VulkanBackend(),
-            // TODO(crbug.com/dawn/942)
-            // There was a compiler error: Buffer block cannot be expressed as any of std430,
-            // std140, scalar, even with enhanced layouts. You can try flattening this block to
-            // support a more flexible layout.
-            // OpenGLBackend(),
+            OpenGLBackend(),
             OpenGLESBackend(),
         },
         {StorageClass::Storage, StorageClass::Uniform},