Infer types for compile-time constant closures.

tests/compiler/dart2js/simple_inferrer_const_closure2_test.dart

 // Copyright (c) 2014, 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 'compiler_helper.dart';
 
 const String TEST = """
 
-method1() {
-  return 42;
-}
-
-method2(a) {  // Called only via [foo2] with a small integer.
+method(a) {  // Called via [foo] with integer then double.
   return a;
 }
 
-const foo1 = method1;
-const foo2 = method2;
+const foo = method;
 
-returnInt1() {
-  return foo1();
-}
-
-returnInt2() {
-  return foo2(54);
+returnNum(x) {
+  return foo(x);
 }
 
 main() {
-  returnInt1();
-  returnInt2();
+  returnNum(10);
+  returnNum(10.5);
 }
 """;
 
 
 void main() {
   Uri uri = new Uri(scheme: 'source');
   var compiler = compilerFor(TEST, uri);
   asyncTest(() => compiler.runCompiler(uri).then((_) {
     var typesInferrer = compiler.typesTask.typesInferrer;
 
     checkReturn(String name, type) {
       var element = findElement(compiler, name);
       Expect.equals(type,
           typesInferrer.getReturnTypeOfElement(element).simplify(compiler),
           name);
     }
 
-    checkReturn('method1', compiler.typesTask.uint31Type);
-    checkReturn('returnInt1', compiler.typesTask.uint31Type);
-
-    checkReturn('method2', compiler.typesTask.uint31Type);
-    checkReturn('returnInt2', compiler.typesTask.uint31Type);
+    checkReturn('method', compiler.typesTask.numType);
+    checkReturn('returnNum', compiler.typesTask.numType);
   }));
 }