Extra "" around singleton in {Name|No}MethodError

This was weirdly hard to see in reading MRI's logic where
it adds a break to jump past reinspecting the String it makes
only for singletons (other cases still are module/classes to be
inspected).  This fixes a single spec failure in ruby/language.

Author: enebo

core/src/main/java/org/jruby/RubyNameError.java

@@ -150,17 +150,20 @@ public IRubyObject to_str(ThreadContext context) {
                     if (klass.isSingleton()) {
                         separator = newString(context, "");
                         if (object == runtime.getTopSelf()) {
-                            classTmp = newString(context, "main");
+                            className = newString(context, "main");
                         } else {
-                            classTmp = object.anyToString();
+                            className = (RubyString) object.anyToString();
                         }
                     } else {
                         separator = newString(context, "an instance of ");
                         classTmp = klass.getRealClass();
+                        className = getNameOrInspect(context, classTmp);
                     }
+                } else {
+                    className = getNameOrInspect(context, classTmp);
                 }
 
-                className = getNameOrInspect(context, classTmp);
+
             }
 
             RubyArray arr = RubyArray.newArray(runtime, this.name, description, separator, className);