Fix for interpolation codegen bug

tests/compiler/dart2js_extra/string_interpolation_opt1_test.dart

Index: tests/compiler/dart2js_extra/string_interpolation_opt1_test.dart
diff --git a/tests/compiler/dart2js_extra/string_interpolation_opt1_test.dart b/tests/compiler/dart2js_extra/string_interpolation_opt1_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..329d6330b4115e44b9fbdbb1ce9132e38e0f2bf7
--- /dev/null
+++ b/tests/compiler/dart2js_extra/string_interpolation_opt1_test.dart
@@ -0,0 +1,56 @@
+// Copyright (c) 2014, 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.
+
+import "package:expect/expect.dart";
+import 'dart:math';
+
+// Test that String interpolation works in some optimized cases.
+
+bool get inscrutableFalse => new Random().nextDouble() > 2;
+
+returnsNullOrString(x) {
+  if (inscrutableFalse) return 'hi';
+  if (inscrutableFalse) return null;
+  return x;
+}
+
+returnsNullOrInt(x) {
+  if (inscrutableFalse) return 123;
+  if (inscrutableFalse) return null;
+  return x;
+}
+
+spoil(a) {
+  a[3] = 123;
+  a[4] = 'ddd';
+}
+
+void testString() {
+  var a = new List(100);  // 'null' values in here are JavaScript undefined.
+  spoil(a);
+  var s = returnsNullOrString('hi');
+  var x = a[2];
+  if (x == null) {
+    s = returnsNullOrString(x);
+  }
+
+  Expect.equals('s: null', 's: $s');
+}
+
+void testInt() {
+  var a = new List(100);  // 'null' values in here are JavaScript undefined.
+  spoil(a);
+  var s = returnsNullOrInt(123);
+  var x = a[2];
+  if (x == null) {
+    s = returnsNullOrInt(x);
+  }
+
+  Expect.equals('s: null', 's: $s');
+}
+
+void main() {
+  testInt();
+  testString();
+}