fix issue 1110 (handle void better)

frog/member.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /** A formal parameter to a [Method]. */
 class Parameter {
   FormalNode definition;
   Member method;
 
   String name;
@@ skipping 1217 matching lines @@
       }
     } else {
       if (definition.body == null && !isConstructor && !isNative) {
         world.error('method needs a body', span);
       }
     }
 
     if (isConstructor && !isFactory) {
       returnType = declaringType;
     } else {
-      returnType = resolveType(definition.returnType, false);
+      // This is the one and only place we allow void.
+      returnType = resolveType(definition.returnType, false, allowVoid: true);
     }
     parameters = [];
     for (var formal in definition.formals) {
       // TODO(jimhug): Clean up construction of Parameters.
       var param = new Parameter(formal, this);
       param.resolve();
       parameters.add(param);
     }
 
     if (!isLambda) {
       library._addMember(this);
     }
   }
 
   /** Overriden to ensure that type arguments aren't used in static methods. */
-  Type resolveType(TypeReference node, bool typeErrors) {
+  Type resolveType(TypeReference node, bool typeErrors,
+      [bool allowVoid = false]) {
     Type t = super.resolveType(node, typeErrors);
     if (isStatic && !isFactory && t is ParameterType) {
       world.error('using type parameter in static context.', node.span);
     }
+    if (!allowVoid && t.isVoid) {
+      world.error('"void" only allowed as return type', node.span);
+    }
     return t;
   }
 }
 
 
 class MemberSet {
   final String name;
   final List<Member> members;
   final String jsname;
   final bool isVar;
@@ skipping 317 matching lines @@
   }
 
   void forEach(void f(Member member)) {
     factories.forEach((_, Map constructors) {
       constructors.forEach((_, Member member) {
         f(member);
       });
     });
   }
 }