Handle redirecting factories.

pkg/compiler/lib/src/elements/elements.dart

Index: pkg/compiler/lib/src/elements/elements.dart
diff --git a/pkg/compiler/lib/src/elements/elements.dart b/pkg/compiler/lib/src/elements/elements.dart
index 2e6adb0a7036decbd5204782610cfa91dc16b876..5223189a9274519b9cedf53e26030be701b9f5bc 100644
--- a/pkg/compiler/lib/src/elements/elements.dart
+++ b/pkg/compiler/lib/src/elements/elements.dart
@@ -1236,6 +1236,10 @@ abstract class LocalFunctionElement extends FunctionElement
 /// A constructor.
 abstract class ConstructorElement extends FunctionElement
     implements MemberElement {
+  /// Returns `true` if [effectiveTarget] has been computed for this
+  /// constructor.
+  bool get hasEffectiveTarget;
+
   /// The effective target of this constructor, that is the non-redirecting
   /// constructor that is called on invocation of this constructor.
   ///