Add inference test functionality based on code point id.

pkg/compiler/lib/src/inferrer/builder.dart

Index: pkg/compiler/lib/src/inferrer/builder.dart
diff --git a/pkg/compiler/lib/src/inferrer/builder.dart b/pkg/compiler/lib/src/inferrer/builder.dart
index add6babf74a74fbf539fbd3978dcf5fe415eb628..cf7ea51ecf93bbc0e5f4afdcc7ee23db3bdcd5a1 100644
--- a/pkg/compiler/lib/src/inferrer/builder.dart
+++ b/pkg/compiler/lib/src/inferrer/builder.dart
@@ -2886,7 +2886,7 @@ class ElementGraphBuilder extends ast.Visitor<TypeInformation>
     ast.Node identifier = node.declaredIdentifier;
     Element element = elements.getForInVariable(node);
     Selector selector = elements.getSelector(identifier);
-    TypeMask mask = inTreeData.typeOfSend(identifier);
+    TypeMask mask = inTreeData.typeOfSend(identifier.asSend());
 
     TypeInformation receiverType;
     if (element != null && element.isInstanceMember) {