Preserve isConst when cloning.

pkg/kernel/lib/clone.dart

Index: pkg/kernel/lib/clone.dart
diff --git a/pkg/kernel/lib/clone.dart b/pkg/kernel/lib/clone.dart
index 4cfb9e8e4489dad5fd80d39bb45b16c8c1d25d89..8ef08210c46f6d038fa113f0e3a2ed780897d6d1 100644
--- a/pkg/kernel/lib/clone.dart
+++ b/pkg/kernel/lib/clone.dart
@@ -119,11 +119,13 @@ class CloneVisitor extends TreeVisitor {
   }
 
   visitStaticInvocation(StaticInvocation node) {
-    return new StaticInvocation(node.target, clone(node.arguments));
+    return new StaticInvocation(node.target, clone(node.arguments),
+        isConst: node.isConst);
   }
 
   visitConstructorInvocation(ConstructorInvocation node) {
-    return new ConstructorInvocation(node.target, clone(node.arguments));
+    return new ConstructorInvocation(node.target, clone(node.arguments),
+        isConst: node.isConst);
   }
 
   visitNot(Not node) {