Suppress unnecessary VVL warning.

WebGPU allows having fragment outputs that don't match any attachments
so suppress this warning from the VVLs.

Bug: None
Change-Id: I49d3d876fdbc9e25ff71fd763593c7d810cb248c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/103021
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>

src/dawn/native/vulkan/BackendVk.cpp

@@ -86,6 +86,11 @@ constexpr SkippedMessage kSkippedMessages[] = {
     // http://anglebug.com/7513
     {"VUID-VkGraphicsPipelineCreateInfo-pStages-06896",
      "contains fragment shader state, but stages"},
+
+    // A warning that's generated on valid usage of the WebGPU API where a fragment output doesn't
+    // have a corresponding attachment
+    {"UNASSIGNED-CoreValidation-Shader-OutputNotConsumed",
+     "fragment shader writes to output location 0 with no matching attachment"},
 };
 
 namespace dawn::native::vulkan {