After a dynamic call, refine the receiver type by looking at the potential targets of that call.

sdk/lib/_internal/compiler/implementation/universe/function_set.dart

Index: sdk/lib/_internal/compiler/implementation/universe/function_set.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/universe/function_set.dart	(revision 22031)
+++ sdk/lib/_internal/compiler/implementation/universe/function_set.dart	(working copy)
@@ -44,6 +44,13 @@
         : false;
   }
 
+  Iterable<ClassElement> findTargets(Selector selector) {
+    SourceString name = selector.name;
+    FunctionSetNode node = nodes[name];
+    if (node == null) return const <ClassElement>[];
+    return node.query(selector, compiler, null).classes;
+  }
+
   /**
    * Returns an object that allows iterating over all the functions
    * that may be invoked with the given [selector].
@@ -179,18 +186,21 @@
     }
     cache[selector] = result = (functions != null)
         ? newQuery(functions, selector, compiler)
-        : const FunctionSetQuery(const <Element>[]);
+        : const FunctionSetQuery(const <Element>[],
+                                 const <ClassElement>[]);
     return result;
   }
 
   FunctionSetQuery newQuery(List<Element> functions,
                             Selector selector,
                             Compiler compiler) {
-    return new FunctionSetQuery(functions);
+    return new FunctionSetQuery(
+        functions, <ClassElement>[compiler.objectClass]);
   }
 }
 
 class FunctionSetQuery {
   final List<Element> functions;
-  const FunctionSetQuery(this.functions);
+  final List<ClassElement> classes;  
+  const FunctionSetQuery(this.functions, this.classes);
 }