Use Reflection.Emit accessors when dynamic code is supported

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/MemberAccessor.cs

@@ -31,13 +31,8 @@ static MemberAccessor Initialize()
                 {
                     MemberAccessor value =
 #if NET
-                        // On platforms where dynamic code is supported but not compiled to native code
-                        // (e.g. the Mono interpreter, WASM and iOS), the IL emitted by the Reflection.Emit
-                        // based accessor is only interpreted, offering no throughput benefit over plain
-                        // reflection while still pulling in the Reflection.Emit stack. Gating on
-                        // IsDynamicCodeCompiled (rather than IsDynamicCodeSupported) keeps Reflection.Emit
-                        // on JIT-backed runtimes but lets the trimmer remove it everywhere else.
-                        RuntimeFeature.IsDynamicCodeCompiled ?
+                        // if dynamic code isn't supported, fallback to reflection
+                        RuntimeFeature.IsDynamicCodeSupported ?
                             new ReflectionEmitCachingMemberAccessor() :
                             new ReflectionMemberAccessor();
 #elif NETFRAMEWORK