Whitelist send_with_u8_array slice

Fixes rustwasm#2014

Author: chinedufn

crates/webidl/src/lib.rs

@@ -244,6 +244,8 @@ fn immutable_slice_whitelist() -> BTreeSet<&'static str> {
         "clearBufferfv",
         "clearBufferiv",
         "clearBufferuiv",
+        // WebSocket
+        "send_with_u8_array",
         // TODO: Add another type's functions here. Leave a comment header with the type name
     ])
 }