Implement tracing for function expressions and statements, and infer types of parameters of these c…

sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart

Index: sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart	(revision 31156)
+++ sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart	(working copy)
@@ -49,6 +49,8 @@
 
   T allocateMap(T keyType, T valueType, T type);
 
+  T allocateClosure(Node node, Element element);
+
   /**
    * Returns the least upper bound between [firstType] and
    * [secondType].
@@ -271,6 +273,10 @@
   bool every(bool f(T type)) {
     return positional.every(f) && named.values.every(f);
   }
+
+  bool contains(T type) {
+    return positional.contains(type) || named.containsValue(type);
+  }
 }
 
 abstract class MinimalInferrerEngine<T> {
@@ -734,6 +740,11 @@
       return thisType;
     } else if (node.isSuper()) {
       return superType;
+    } else {
+      Element element = elements[node];
+      if (Elements.isLocal(element)) {
+        return locals.use(element);
+      }
     }
   }