Make super.foo= erroneous if they are not assignable.

pkg/compiler/lib/src/tree/nodes.dart

Index: pkg/compiler/lib/src/tree/nodes.dart
diff --git a/pkg/compiler/lib/src/tree/nodes.dart b/pkg/compiler/lib/src/tree/nodes.dart
index d6222eb6c3a6bdb2e69186ad46c3bad97758cbc7..c13587a4bd7a9c8c8868024ddc68652f84ab885c 100644
--- a/pkg/compiler/lib/src/tree/nodes.dart
+++ b/pkg/compiler/lib/src/tree/nodes.dart
@@ -383,9 +383,8 @@ class Send extends Expression with StoredTreeElementMixin {
     return (argumentsNode == null) ? -1 : argumentsNode.slowLength();
   }
 
-  bool get isSuperCall {
-    return receiver != null && receiver.isSuper();
-  }
+  bool get isSuperCall => receiver != null && receiver.isSuper();
+  bool get isThisCall => receiver != null && receiver.isThis();
   bool get isOperator => selector is Operator;
   bool get isPropertyAccess => argumentsNode == null;
   bool get isFunctionObjectInvocation => selector == null;