Fix simpleToString() per Tim's desire:

Cope with a bogus passed-in property name.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5820 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/as/com/threerings/util/StringUtil.as

@@ -414,7 +414,12 @@ public class StringUtil
             if (appended) {
                 buf.append(", ");
             }
-            buf.append(varName, "=", obj[varName]);
+            buf.append(varName, "=");
+            try {
+                buf.append(obj[varName]);
+            } catch (re :ReferenceError) {
+                buf.append("<ReferenceError>");
+            }
             appended = true;
         }
     }