Use entities in code_emitter_task

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 581a1b2f4d1bec042e5ba1e2940fbc71a4156b6e..0595e8d4962d3218522e2eb3a4be36fe778d9865 100644
--- a/pkg/compiler/lib/src/universe/use.dart
+++ b/pkg/compiler/lib/src/universe/use.dart
@@ -329,6 +329,9 @@ class StaticUse {
   }
 
   /// Unknown use of [element].
+  ///
+  /// Avoid using this, if possible: Use one of the other constructor which more
+  /// precisely capture why [element] is used.
   @deprecated
   factory StaticUse.foreignUse(Entity element) {
     return new StaticUse.internal(element, StaticUseKind.GENERAL);