When a phi is generated at use site, the names of its inputs must be freed by the user of the phi.

tests/language/issue10204_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Regression test for dart2js that used to miscompile
+// [A.visitInvokeDynamicMethod].
+
+import "package:expect/expect.dart";
+
+var a = 2;
+
+class Tupe {
+  const Tupe();
+  get instructionType => a == 2 ? this : new A();
+  refine(a, b) => '$a$b';
+}
+
+class Node {
+  final selector = null;
+  var inputs = {"a": const Tupe(), "b": const Tupe() };
+  bool isCallOnInterceptor;
+
+  getDartReceiver() {
+    return isCallOnInterceptor ? inputs["a"] : inputs["b"];
+  }
+}
+
+class A {
+  visitInvokeDynamicMethod(node) {
+    var receiverType = node.getDartReceiver().instructionType;
+    return receiverType.refine(node.selector, node.selector);
+  }
+}
+
+main() {
+  Expect.equals('nullnull',
+                [new A()].last.visitInvokeDynamicMethod(new Node()));
+}