dart2js cps: Fix default values for forwarding constructors.

pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
index 759ed6c13fe8e99f0c7880fe199ac8b2424eff44..0c559d9f0515ed75271ccc83f8d66226a61453a1 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
@@ -3637,10 +3637,11 @@ class JsIrBuilderVisitor extends IrBuilderVisitor {
       _) {
     List<ir.Primitive> arguments =
         node.send.arguments.mapToList(visit, growable:false);
-    arguments = normalizeStaticArguments(
-        callStructure, constructor, arguments);
+    // Use default values from the effective target, not the immediate target.
+    ConstructorElement target = constructor.effectiveTarget;
+    arguments = normalizeStaticArguments(callStructure, target, arguments);
     return irBuilder.buildConstructorInvocation(
-        constructor.effectiveTarget,
+        target,
         callStructure,
         constructor.computeEffectiveTargetType(type),
         arguments);