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

tests/compiler/dart2js/simple_inferrer_test.dart

 // Copyright (c) 2013, 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.
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import
     '../../../sdk/lib/_internal/compiler/implementation/types/types.dart'
     show TypeMask;
 
@@ skipping 703 matching lines @@
     }
     var interceptorType =
         findTypeMask(compiler, 'Interceptor', 'nonNullSubclass');
 
     checkReturn('returnNum1', typesTask.numType);
     checkReturn('returnNum2', typesTask.numType);
     checkReturn('returnInt1', typesTask.uint31Type);
     checkReturn('returnInt2', typesTask.uint31Type);
     checkReturn('returnDouble', typesTask.doubleType);
     checkReturn('returnGiveUp', interceptorType);
-    checkReturn('returnInt5', typesTask.intType);
-    checkReturn('returnInt6', typesTask.intType);
+    checkReturn('returnInt5', typesTask.positiveIntType);
+    checkReturn('returnInt6', typesTask.positiveIntType);
     checkReturn('returnIntOrNull', typesTask.uint31Type.nullable());
     checkReturn('returnInt3', typesTask.uint31Type);
     checkReturn('returnDynamic', typesTask.dynamicType);
     checkReturn('returnInt4', typesTask.uint31Type);
-    checkReturn('returnInt7', typesTask.intType);
-    checkReturn('returnInt8', typesTask.intType);
+    checkReturn('returnInt7', typesTask.positiveIntType);
+    checkReturn('returnInt8', typesTask.positiveIntType);
     checkReturn('returnEmpty1', const TypeMask.nonNullEmpty());
     checkReturn('returnEmpty2', const TypeMask.nonNullEmpty());
     TypeMask intType = new TypeMask.nonNullSubtype(compiler.intClass);
     checkReturn('testIsCheck1', intType);
     checkReturn('testIsCheck2', intType);
     checkReturn('testIsCheck3', intType.nullable());
     checkReturn('testIsCheck4', intType);
     checkReturn('testIsCheck5', intType);
     checkReturn('testIsCheck6', typesTask.dynamicType);
     checkReturn('testIsCheck7', intType);
@@ skipping 31 matching lines @@
     checkReturn('testSwitch1', typesTask.intType
         .union(typesTask.doubleType, compiler)
         .nullable().simplify(compiler));
     checkReturn('testSwitch2', typesTask.uint31Type);
     checkReturn('testSwitch3', interceptorType.nullable());
     checkReturn('testSwitch4', typesTask.uint31Type);
     checkReturn('testSwitch5', typesTask.uint31Type);
     checkReturn('testContinue1', interceptorType.nullable());
     checkReturn('testBreak1', interceptorType.nullable());
     checkReturn('testContinue2', interceptorType.nullable());
-    checkReturn('testBreak2', typesTask.intType.nullable());
+    checkReturn('testBreak2', typesTask.positiveIntType.nullable());
     checkReturn('testReturnElementOfConstList1', typesTask.uint31Type);
     checkReturn('testReturnElementOfConstList2', typesTask.uint31Type);
     checkReturn('testReturnItselfOrInt', typesTask.uint31Type);
     checkReturn('testReturnInvokeDynamicGetter', typesTask.dynamicType);
 
     checkReturn('testDoWhile1', typesTask.stringType);
     checkReturn('testDoWhile2', typesTask.nullType);
     checkReturn('testDoWhile3', typesTask.uint31Type);
     checkReturn('testDoWhile4', typesTask.numType);
 
     checkReturnInClass(String className, String methodName, type) {
       var cls = findElement(compiler, className);
       var element = cls.lookupLocalMember(methodName);
       Expect.equals(type,
           typesInferrer.getReturnTypeOfElement(element).simplify(compiler),
           '$className:$methodName');
     }
 
-    checkReturnInClass('A', 'returnInt1', typesTask.intType);
-    checkReturnInClass('A', 'returnInt2', typesTask.intType);
-    checkReturnInClass('A', 'returnInt3', typesTask.intType);
-    checkReturnInClass('A', 'returnInt4', typesTask.intType);
-    checkReturnInClass('A', 'returnInt5', typesTask.intType);
-    checkReturnInClass('A', 'returnInt6', typesTask.intType);
+    checkReturnInClass('A', 'returnInt1', typesTask.positiveIntType);
+    checkReturnInClass('A', 'returnInt2', typesTask.positiveIntType);
+    checkReturnInClass('A', 'returnInt3', typesTask.positiveIntType);
+    checkReturnInClass('A', 'returnInt4', typesTask.positiveIntType);
+    checkReturnInClass('A', 'returnInt5', typesTask.positiveIntType);
+    checkReturnInClass('A', 'returnInt6', typesTask.positiveIntType);
     checkReturnInClass('A', '==', interceptorType);
 
-    checkReturnInClass('B', 'returnInt1', typesTask.intType);
-    checkReturnInClass('B', 'returnInt2', typesTask.intType);
-    checkReturnInClass('B', 'returnInt3', typesTask.intType);
-    checkReturnInClass('B', 'returnInt4', typesTask.intType);
-    checkReturnInClass('B', 'returnInt5', typesTask.intType);
-    checkReturnInClass('B', 'returnInt6', typesTask.intType);
-    checkReturnInClass('B', 'returnInt7', typesTask.intType);
-    checkReturnInClass('B', 'returnInt8', typesTask.intType);
+    checkReturnInClass('B', 'returnInt1', typesTask.positiveIntType);
+    checkReturnInClass('B', 'returnInt2', typesTask.positiveIntType);
+    checkReturnInClass('B', 'returnInt3', typesTask.positiveIntType);
+    checkReturnInClass('B', 'returnInt4', typesTask.positiveIntType);
+    checkReturnInClass('B', 'returnInt5', typesTask.positiveIntType);
+    checkReturnInClass('B', 'returnInt6', typesTask.positiveIntType);
+    checkReturnInClass('B', 'returnInt7', typesTask.positiveIntType);
+    checkReturnInClass('B', 'returnInt8', typesTask.positiveIntType);
     checkReturnInClass('B', 'returnInt9', typesTask.uint31Type);
 
     checkFactoryConstructor(String className, String factoryName) {
       var cls = findElement(compiler, className);
       var element = cls.localLookup(factoryName);
       Expect.equals(new TypeMask.nonNullExact(cls),
                     typesInferrer.getReturnTypeOfElement(element));
     }
     checkFactoryConstructor('A', '');
 
     checkReturn('testCascade1', typesTask.growableListType);
     checkReturn('testCascade2', new TypeMask.nonNullExact(
         findElement(compiler, 'CascadeHelper')));
     checkReturn('testSpecialization1', typesTask.numType);
     checkReturn('testSpecialization2', typesTask.dynamicType);
     checkReturn('testSpecialization3', typesTask.uint31Type.nullable());
     checkReturn('testReturnNull1', typesTask.nullType);
     checkReturn('testReturnNull2', typesTask.nullType);
     checkReturn('testReturnNull3', typesTask.dynamicType);
     checkReturn('testReturnNull4', typesTask.nullType);
     checkReturn('testReturnNull5', typesTask.nullType);
     checkReturn('testReturnNull6', typesTask.dynamicType);
   }));
 }