Infer types of catpured variables and use the types in the SSA builder.

tests/compiler/dart2js/simple_inferrer_closure_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';
 
 const String TEST = """
 returnInt1() {
   var a = 42;
   var f = () {
@@ skipping 26 matching lines @@
   var g = () {
     a = 'foo';
   };
   return a;
 }
 
 returnInt3() {
   var a = 42;
   if (a == 53) {
     var f = () {
-      a = 32;
+      return a;
     };
   }
   return a;
 }
 
 returnDyn3() {
   var a = 42;
   if (a == 53) {
     var f = () {
       a = 'foo';
     };
   }
   return a;
 }
 
+returnInt4() {
+  var a = 42;
+  g() { return a; }
+  return g();
+}
+
 main() {
   returnInt1();
   returnDyn1();
   returnInt2();
   returnDyn2();
   returnInt3();
   returnDyn3();
+  returnInt4();
 }
 """;
 
 
 void main() {
   Uri uri = new Uri.fromComponents(scheme: 'source');
   var compiler = compilerFor(TEST, uri);
   compiler.runCompiler(uri);
   var typesInferrer = compiler.typesTask.typesInferrer;
 
   checkReturn(String name, type) {
     var element = findElement(compiler, name);
     Expect.equals(type, typesInferrer.returnTypeOf[element]);
   }
 
   checkReturn('returnInt1', compiler.intClass);
-  checkReturn('returnInt2', compiler.intClass);
+  // TODO(ngeoffray): We don't use types of mutated captured

[kasperl, 2013/03/05 08:26:44]

So you'd like to fix this to make returnInt2 return an int? I guess so.

[ngeoffray, 2013/03/05 09:02:31]

Depends on the TODO I added in the types inferrer: once we definitely know the
type of a mutated variable, should we re-analyze the method?

I guess this should not blow up analysis time, mutated variables in closures are
very local, and does not involve re-analyzing a lot of methods.

+  // variables anymore, because they could lead to optimistic results
+  // needing to be re-analyzed.
+  checkReturn('returnInt2', compiler.dynamicClass);
   checkReturn('returnInt3', compiler.intClass);
+  checkReturn('returnInt4', compiler.intClass);
 
   checkReturn('returnDyn1', compiler.dynamicClass);
   checkReturn('returnDyn2', compiler.dynamicClass);
   checkReturn('returnDyn3', compiler.dynamicClass);
-
-  print(typesInferrer.returnTypeOf);
 }