Implement CHA through type mask and TypedSelector in the simple type inferrer.

tests/compiler/dart2js/simple_inferrer_postfix_prefix_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 'compiler_helper.dart';
 import 'parser_helper.dart';
 
 const String TEST = """
 
 class A {
   get foo => 'string';
   set foo(value) {}
   operator[](index) => 'string';
   operator[]=(index, value) {}
   
-  returnString1() => foo--;
+  returnDynamic1() => foo--;
   returnNum1() => --foo;
   returnNum2() => foo -= 42;
 
-  returnDynamic1() => this[index]--;
+  returnDynamic2() => this[index]--;
   returnNum3() => --this[index];
   returnNum4() => this[index] -= 42;
 
-  returnDynamic2() => this.bar--;
+  returnDynamic3() => this.bar--;
   returnNum5() => --this.bar;
   returnNum6() => this.bar -= 42;
 }
 
 class B extends A {
+  get foo() => 42;
+  operator[](index) => 42;
+
   returnString1() => super.foo--;
-  returnNum1() => --super.foo;
-  returnNum2() => super.foo -= 42;
+  returnDynamic1() => --super.foo;
+  returnDynamic2() => super.foo -= 42;
 
-  returnDynamic1() => super[index]--;
-  returnNum3() => --super[index];
-  returnNum4() => super[index] -= 42;
+  returnString2() => super[index]--;
+  returnDynamic3() => --super[index];
+  returnDynamic4() => super[index] -= 42;
 }
 
 main() {
   new A()..returnNum1()
          ..returnNum2()
          ..returnNum3()
          ..returnNum4()
          ..returnNum5()
          ..returnNum6()
-         ..returnString1()
          ..returnDynamic1()
-         ..returnDynamic2();
+         ..returnDynamic2()
+         ..returnDynamic3();
 
-  new B()..returnNum1()
-         ..returnNum2()
-         ..returnNum3()
-         ..returnNum4()
-         ..returnString1()
-         ..returnDynamic1();
+  new B()..returnString1()
+         ..returnString2()
+         ..returnDynamic1()
+         ..returnDynamic2()
+         ..returnDynamic3()
+         ..returnDynamic4();
 }
 """;
 
 void main() {
   Uri uri = new Uri.fromComponents(scheme: 'source');
   var compiler = compilerFor(TEST, uri);
   compiler.runCompiler(uri);
   var typesInferrer = compiler.typesTask.typesInferrer;
 
   checkReturnInClass(String className, String methodName, type) {
     var cls = findElement(compiler, className);
     var element = cls.lookupLocalMember(buildSourceString(methodName));
     Expect.equals(type, typesInferrer.returnTypeOf[element]);
   }
 
   checkReturnInClass('A', 'returnNum1', typesInferrer.numType);
   checkReturnInClass('A', 'returnNum2', typesInferrer.numType);
   checkReturnInClass('A', 'returnNum3', typesInferrer.numType);
   checkReturnInClass('A', 'returnNum4', typesInferrer.numType);
   checkReturnInClass('A', 'returnNum5', typesInferrer.numType);
   checkReturnInClass('A', 'returnNum6', typesInferrer.numType);
   checkReturnInClass('A', 'returnDynamic1', typesInferrer.dynamicType);
   checkReturnInClass('A', 'returnDynamic2', typesInferrer.dynamicType);
-  checkReturnInClass('A', 'returnString1', typesInferrer.stringType);
+  checkReturnInClass('A', 'returnDynamic3', typesInferrer.dynamicType);
 
-  checkReturnInClass('B', 'returnNum1', typesInferrer.numType);
-  checkReturnInClass('B', 'returnNum2', typesInferrer.numType);
-  checkReturnInClass('B', 'returnNum3', typesInferrer.numType);
-  checkReturnInClass('B', 'returnNum4', typesInferrer.numType);
   checkReturnInClass('B', 'returnString1', typesInferrer.stringType);
+  checkReturnInClass('B', 'returnString2', typesInferrer.stringType);
   checkReturnInClass('B', 'returnDynamic1', typesInferrer.dynamicType);
+  checkReturnInClass('B', 'returnDynamic2', typesInferrer.dynamicType);
+  checkReturnInClass('B', 'returnDynamic3', typesInferrer.dynamicType);
+  checkReturnInClass('B', 'returnDynamic4', typesInferrer.dynamicType);
 }