Use JavaScript runtime semantics when constant folding.

lib/compiler/implementation/native_handler.dart

Index: lib/compiler/implementation/native_handler.dart
diff --git a/lib/compiler/implementation/native_handler.dart b/lib/compiler/implementation/native_handler.dart
index 65500cb0ba13582f4f4793f1d2031f4dba73ce52..18a67d7d6150d143cf6a91e9fb5049687c8941a0 100644
--- a/lib/compiler/implementation/native_handler.dart
+++ b/lib/compiler/implementation/native_handler.dart
@@ -195,7 +195,9 @@ void handleSsaNative(SsaBuilder builder, Expression nativeBody) {
 
   HInstruction convertDartClosure(Element parameter, FunctionType type) {
     HInstruction local = builder.localsHandler.readLocal(parameter);
-    HInstruction arity = builder.graph.addConstantInt(type.computeArity());
+    Constant arityConstant =
+        builder.constantSystem.createInt(type.computeArity());
+    HInstruction arity = builder.graph.addConstant(arityConstant);
     // TODO(ngeoffray): For static methods, we could pass a method with a
     // defined arity.
     Element helper = builder.interceptors.getClosureConverter();