Disable MultipleWriteThenMultipleReadTests for D3D12 + tint

Bug: tint:686
Change-Id: Iaca48aa7fb4cddbc008d66a248d01a6e4d36f5ea
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/46372
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/tests/end2end/GpuMemorySynchronizationTests.cpp

@@ -493,6 +493,13 @@ constexpr int kVertexBufferStride = 4 * sizeof(float);
 
 class MultipleWriteThenMultipleReadTests : public DawnTest {
   protected:
+    void SetUp() {
+        DawnTest::SetUp();
+
+        // TODO(crbug.com/tint/686): error: unsupported struct member decoration
+        DAWN_SKIP_TEST_IF(IsD3D12() && HasToggleEnabled("use_tint_generator"));
+    }
+
     wgpu::Buffer CreateZeroedBuffer(uint64_t size, wgpu::BufferUsage usage) {
         wgpu::BufferDescriptor srcDesc;
         srcDesc.size = size;