Add HCreateBox

pkg/compiler/lib/src/ssa/ssa_tracer.dart

Index: pkg/compiler/lib/src/ssa/ssa_tracer.dart
diff --git a/pkg/compiler/lib/src/ssa/ssa_tracer.dart b/pkg/compiler/lib/src/ssa/ssa_tracer.dart
index d4ac68cac00649ef4f496271021770fc36e09780..00e0fac7671b30ff8efdc62449c4be63bf70d69d 100644
--- a/pkg/compiler/lib/src/ssa/ssa_tracer.dart
+++ b/pkg/compiler/lib/src/ssa/ssa_tracer.dart
@@ -205,6 +205,10 @@ class HInstructionStringifier implements HVisitor<String> {
     return handleGenericInvoke("Create", "${node.element.name}", node.inputs);
   }
 
+  String visitCreateBox(HCreateBox node) {
+    return handleGenericInvoke("CreateBox", "", node.inputs);
+  }
+
   String visitDivide(HDivide node) => handleInvokeBinary(node, 'Divide');
 
   String visitExit(HExit node) => "Exit";