Implement super.foo = expression.

dart/lib/compiler/implementation/ssa/builder.dart

Index: dart/lib/compiler/implementation/ssa/builder.dart
diff --git a/dart/lib/compiler/implementation/ssa/builder.dart b/dart/lib/compiler/implementation/ssa/builder.dart
index 3eb295d1827b7ce550294162b1f1e21646ef6ae2..fae30e27db03de34ff5af27137d4e76e7d4c6eb7 100644
--- a/dart/lib/compiler/implementation/ssa/builder.dart
+++ b/dart/lib/compiler/implementation/ssa/builder.dart
@@ -2421,7 +2421,11 @@ class SsaBuilder extends ResolvedVisitor implements Visitor {
       add(target);
       var inputs = <HInstruction>[target, context];
       addDynamicSendArgumentsToList(node, inputs);
-      push(new HInvokeSuper(inputs));
+      if (node.assignmentOperator.source.stringValue !== '=') {
+        compiler.unimplemented('complex super assignment',
+                               node: node.assignmentOperator);
+      }
+      push(new HInvokeSuper(inputs, isSetter: true));
     } else if (node.isIndex) {
       if (!methodInterceptionEnabled) {
         assert(op.source.stringValue === '=');