Update assert failure messages

test/intl402/NumberFormat/prototype/format/this-value-not-numberformat.js

@@ -16,6 +16,6 @@ invalidTargets.forEach(target => {
   assert.throws(
     TypeError,
     () => fn.call(target),
-    `Calling format getter on ${target} was not rejected.`
+    `Calling format getter on ${target} should throw a TypeError.`
   );
 });

test/intl402/NumberFormat/prototype/formatToParts/this-value-not-numberformat.js

@@ -16,6 +16,6 @@ invalidTargets.forEach(target => {
   assert.throws(
     TypeError,
     () => fn.call(target),
-    `Calling formatToParts on ${target} was not rejected.`
+    `Calling formatToParts on ${target} should throw a TypeError.`
   );
 });

test/intl402/NumberFormat/prototype/resolvedOptions/this-value-not-numberformat.js

@@ -16,6 +16,6 @@ invalidTargets.forEach(target => {
   assert.throws(
     TypeError,
     () => fn.call(target),
-    `Calling resolvedOptions on ${target} was not rejected.`
+    `Calling resolvedOptions on ${target} should throw a TypeError.`
   );
 });