[wasm-simd] Add anyref subtype

Bug: v8:10347
Change-Id: I46890321944cd861f7f8f193e5e499d4d9cd6aea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2155156Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67252}

include/js_protocol.pdl

@@ -980,6 +980,7 @@ domain Runtime
         f32
         f64
         v128
+        anyref
       # Object class (constructor) name. Specified for `object` type values only.
       optional string className
       # Remote object value in case of primitive values or JSON values (if it was requested).