Replace forEach() with for ... of in test-whatwg-encoding-custom-textdecoder-utf16-surrogates.js

From https://docs.google.com/spreadsheets/d/1mqLZafbDSI_2h6hijO4IYxoibjayzHYt__ZMbVc1s2A/edit#gid=0

Author: alexweej

test/parallel/test-whatwg-encoding-custom-textdecoder-utf16-surrogates.js

@@ -43,7 +43,7 @@ const bad = [
   },
 ];
 
-bad.forEach((t) => {
+for (const t of bad) {
   assert.throws(
     () => {
       new TextDecoder(t.encoding, { fatal: true })
@@ -53,4 +53,4 @@ bad.forEach((t) => {
       name: 'TypeError'
     }
   );
-});
+}