Add missing implementations.

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

Index: pkg/compiler/lib/src/elements/modelx.dart
diff --git a/pkg/compiler/lib/src/elements/modelx.dart b/pkg/compiler/lib/src/elements/modelx.dart
index 06368b571de57317179c1e413480a4ff2dd3a19f..f5e691b8f81ac4b02b8c9d19fe3f67be057295ec 100644
--- a/pkg/compiler/lib/src/elements/modelx.dart
+++ b/pkg/compiler/lib/src/elements/modelx.dart
@@ -283,6 +283,10 @@ class ErroneousElementX extends ElementX implements ErroneousElement {
 
   bool get isSynthesized => true;
 
+  bool get isCyclicRedirection => false;
+
+  PrefixElement get redirectionDeferredPrefix => null;
+
   AbstractFieldElement abstractField;
 
   unsupported() {
@@ -414,6 +418,10 @@ class ErroneousConstructorElementX extends ErroneousElementX
     throw new UnsupportedError("nestedClosures=");
   }
 
+  set redirectionDeferredPrefix(_) {
+    throw new UnsupportedError("redirectionDeferredPrefix=");
+  }
+
   bool get hasNoBody => false;
 
   bool get _hasNoBody => false;