Add another type JSPositiveInt to show a range analysis in the inferrer would be very beneficial :-…

sdk/lib/_internal/compiler/implementation/compiler.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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 238 matching lines @@
   ClassElement get fixedListImplementation => compiler.listClass;
   ClassElement get constListImplementation => compiler.listClass;
   ClassElement get mapImplementation => compiler.mapClass;
   ClassElement get constMapImplementation => compiler.mapClass;
   ClassElement get functionImplementation => compiler.functionClass;
   ClassElement get typeImplementation => compiler.typeClass;
   ClassElement get boolImplementation => compiler.boolClass;
   ClassElement get nullImplementation => compiler.nullClass;
   ClassElement get uint32Implementation => compiler.intClass;
   ClassElement get uint31Implementation => compiler.intClass;
+  ClassElement get positiveIntImplementation => compiler.intClass;
 
   ClassElement defaultSuperclass(ClassElement element) => compiler.objectClass;
 
   bool isDefaultNoSuchMethodImplementation(Element element) {
     assert(element.name == Compiler.NO_SUCH_METHOD);
     ClassElement classElement = element.getEnclosingClass();
     return classElement == compiler.objectClass;
   }
 
   bool isInterceptorClass(ClassElement element) => false;
@@ skipping 1386 matching lines @@
 
   void close() {}
 
   toString() => name;
 
   /// Convenience method for getting an [api.CompilerOutputProvider].
   static NullSink outputProvider(String name, String extension) {
     return new NullSink('$name.$extension');
   }
 }