Record the dependency of a implicit constructor to its superclass.

sdk/lib/_internal/compiler/implementation/world.dart

Index: sdk/lib/_internal/compiler/implementation/world.dart
diff --git a/sdk/lib/_internal/compiler/implementation/world.dart b/sdk/lib/_internal/compiler/implementation/world.dart
index 91a95d263d5a580e78d02fd9cb8c5db0f8a2f65a..033c95ba404981cbe512c2a03a31ccb36240b2d5 100644
--- a/sdk/lib/_internal/compiler/implementation/world.dart
+++ b/sdk/lib/_internal/compiler/implementation/world.dart
@@ -273,4 +273,9 @@ class World {
   bool getCannotThrow(Element element) {
     return elementsThatCannotThrow.contains(element);
   }
+
+  void registerImplicitSuperCall(TreeElements elements,
+                                 FunctionElement superConstructor) {
+    elements.otherDependencies.add(superConstructor);
+  }
 }