Update JsString::try_from to use new dyn_ref

Author: RReverser

crates/js-sys/src/lib.rs

@@ -3515,11 +3515,7 @@ impl JsString {
     /// If this JS value is not an instance of a string then this returns
     /// `None`.
     pub fn try_from(val: &JsValue) -> Option<&JsString> {
-        if val.is_string() {
-            Some(unsafe { mem::transmute(val) })
-        } else {
-            None
-        }
+        val.dyn_ref()
     }
 
     /// Returns whether this string is a valid UTF-16 string.