Register closures using StaticUse.

pkg/compiler/lib/src/universe/use.dart

Index: pkg/compiler/lib/src/universe/use.dart
diff --git a/pkg/compiler/lib/src/universe/use.dart b/pkg/compiler/lib/src/universe/use.dart
index deee3a26c2c0f4ed804dbc9a604c2710f5905cdc..b619d5a9672cb026bf41c8e1a3912d5db512e729 100644
--- a/pkg/compiler/lib/src/universe/use.dart
+++ b/pkg/compiler/lib/src/universe/use.dart
@@ -72,6 +72,7 @@ enum StaticUseKind {
   SUPER_TEAR_OFF,
   FIELD_GET,
   FIELD_SET,
+  CLOSURE,
 }
 
 /// Statically known use of an [Element].
@@ -232,6 +233,11 @@ class StaticUse {
     return new StaticUse._(element, StaticUseKind.FIELD_SET);
   }
 
+  /// Read of a local function [element].
+  factory StaticUse.closure(LocalFunctionElement element) {
+    return new StaticUse._(element, StaticUseKind.CLOSURE);
+  }
+
   /// Unknown use of [element].
   @deprecated
   factory StaticUse.foreignUse(Element element) {