Implement super calls.

frog/leg/ssa/nodes.dart

Index: frog/leg/ssa/nodes.dart
diff --git a/frog/leg/ssa/nodes.dart b/frog/leg/ssa/nodes.dart
index e5ab8ac70cc400914689cbe0e5c90039089af1cc..9c7cb24dd4ef93758a02125b715ef73e58d5d428 100644
--- a/frog/leg/ssa/nodes.dart
+++ b/frog/leg/ssa/nodes.dart
@@ -28,6 +28,7 @@ interface HVisitor<R> {
   R visitInvokeDynamicSetter(HInvokeDynamicSetter node);
   R visitInvokeInterceptor(HInvokeInterceptor node);
   R visitInvokeStatic(HInvokeStatic node);
+  R visitInvokeSuper(HInvokeSuper node);
   R visitLess(HLess node);
   R visitLessEqual(HLessEqual node);
   R visitLoad(HLoad node);
@@ -222,6 +223,7 @@ class HBaseVisitor extends HGraphVisitor implements HVisitor {
   visitInvokeInterceptor(HInvokeInterceptor node)
       => visitInvokeStatic(node);
   visitInvokeStatic(HInvokeStatic node) => visitInvoke(node);
+  visitInvokeSuper(HInvokeSuper node) => visitInvoke(node);
   visitLess(HLess node) => visitRelational(node);
   visitLessEqual(HLessEqual node) => visitRelational(node);
   visitLoad(HLoad node) => visitInstruction(node);
@@ -1018,6 +1020,12 @@ class HInvokeStatic extends HInvoke {
   bool hasExpectedType() => builtin;
 }
 
+class HInvokeSuper extends HInvokeStatic {
+  HInvokeSuper(inputs) : super(inputs);
+  toString() => 'invoke super: ${element.name}';
+  accept(HVisitor visitor) => visitor.visitInvokeSuper(this);
+}
+
 class HInvokeInterceptor extends HInvokeStatic {
   final String name;
   final bool getter;