Add support for superSend to the new IR and dart backend.

sdk/lib/_internal/compiler/implementation/dart_backend/tree_tracer.dart

Index: sdk/lib/_internal/compiler/implementation/dart_backend/tree_tracer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_backend/tree_tracer.dart b/sdk/lib/_internal/compiler/implementation/dart_backend/tree_tracer.dart
index 018996ad1808673d9feafaae8173881c8cdc3d3c..91bca1aeb243151aec8f0a5fd8095a08d8f9ed83 100644
--- a/sdk/lib/_internal/compiler/implementation/dart_backend/tree_tracer.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart_backend/tree_tracer.dart
@@ -57,6 +57,7 @@ class BlockCollector extends Visitor {
   visitVariable(Variable node) {}
   visitInvokeStatic(InvokeStatic node) {}
   visitInvokeMethod(InvokeMethod node) {}
+  visitInvokeSuperMethod(InvokeSuperMethod node) {}
   visitInvokeConstructor(InvokeConstructor node) {}
   visitConcatenateStrings(ConcatenateStrings node) {}
   visitLiteralList(LiteralList node) {}
@@ -304,6 +305,13 @@ class SubexpressionVisitor extends ExpressionVisitor<String> {
     return "$receiver.$name($args)";
   }
 
+  String visitInvokeSuperMethod(InvokeSuperMethod node) {
+    String receiver = node.receiver.accept(this);
+    String name = node.selector.name;
+    String args = formatArguments(node);
+    return "super.$name($args)";
+  }
+
   String visitInvokeConstructor(InvokeConstructor node) {
     String callName;
     if (node.target.name.isEmpty) {