Add test for util.byteToChar() and fix error msg.

testing/resources/javascript/util_bytetochar.in

Index: testing/resources/javascript/util_bytetochar.in
diff --git a/testing/resources/javascript/apply.in b/testing/resources/javascript/util_bytetochar.in
similarity index 51%
copy from testing/resources/javascript/apply.in
copy to testing/resources/javascript/util_bytetochar.in
index 1342c1af4e71c86dfd01b091d0f9fbe68cebfe69..a9adfbccaf72a01349c5639c46afc42046bed7da 100644
--- a/testing/resources/javascript/apply.in
+++ b/testing/resources/javascript/util_bytetochar.in
@@ -34,36 +34,37 @@ endobj
 {{object 11 0}} <<
 >>
 stream
-app.alert('Applying to util itself - should succeed');
-try {
-  app.alert(util.byteToChar.apply(util, [65]));
-}
-catch (e) {
-  app.alert('Caught: ' + e);
-}
-
-app.alert('Applying to array - should throw');
-try {
-  app.alert(util.byteToChar.apply([], [65]));
-}
-catch (e) {
-  app.alert('Caught: ' + e);
+function TestOneInput(x) {
+  try {
+    var s = util.byteToChar(x);
+    if (s.length) {
+      s = s.charCodeAt(0);
+    }
+    app.alert(x + " => " + s);
+  }
+  catch (e) {
+    app.alert(x + ": Caught error: " + e);
+  }
 }
-
-app.alert('Applying to number - should throw');
+TestOneInput(0);
+TestOneInput(65);
+TestOneInput(127);
+TestOneInput(128);
+TestOneInput(255);
+TestOneInput(256);
+TestOneInput(40000000);
+TestOneInput(-1);
 try {
-  app.alert(util.byteToChar.apply(7, [65]));
+  util.byteToChar();
 }
 catch (e) {
-  app.alert('Caught: ' + e);
+  app.alert("Caught expected error: " + e);
 }
-
-app.alert('Applying to wrong native obj - should throw');
 try {
-  app.alert(util.byteToChar.apply(app, [65]));
+  util.byteToChar({x:39});
 }
 catch (e) {
-  app.alert('Caught: ' + e);
+  app.alert("Caught expected error: " + e);
 }
 endstream
 endobj