[turbofan] Add support for copy-on-write element stores.

src/compiler/verifier.cc

Index: src/compiler/verifier.cc
diff --git a/src/compiler/verifier.cc b/src/compiler/verifier.cc
index cb8a12035af0b7ca11dfeceb9a5ffff565513b42..dabb8e4ffed6afd822f181dbd37be4d8009b2a6c 100644
--- a/src/compiler/verifier.cc
+++ b/src/compiler/verifier.cc
@@ -851,6 +851,11 @@ void Verifier::Visitor::Check(Node* node) {
       CheckValueInputIs(node, 0, Type::PlainNumber());
       CheckUpperIs(node, Type::TaggedPointer());
       break;
+    case IrOpcode::kEnsureWritableFastElements:
+      CheckValueInputIs(node, 0, Type::Any());
+      CheckValueInputIs(node, 1, Type::Internal());
+      CheckUpperIs(node, Type::Internal());
+      break;
     case IrOpcode::kTransitionElementsKind:
       CheckValueInputIs(node, 0, Type::Any());
       CheckValueInputIs(node, 1, Type::Internal());