Avoid merging conditions across loop boundary

tests/compiler/dart2js_extra/27354_test.dart

Index: tests/compiler/dart2js_extra/27354_test.dart
diff --git a/tests/compiler/dart2js_extra/27354_test.dart b/tests/compiler/dart2js_extra/27354_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..942dc49b422169a17067ba1e0cd6ad8ac0f5c770
--- /dev/null
+++ b/tests/compiler/dart2js_extra/27354_test.dart
@@ -0,0 +1,14 @@
+// Copyright (c) 2016, 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 Issue 27354.
+
+int total = 1;
+void inc() => total++ < 10 ? null : throw "do not loop forever!";

[Siggi Cherem (dart-lang), 2016/09/15 00:07:10]

just realized `void` here might be an over statement, probably not an issue, but
feel free to delete it

+
+void main() {
+  // Problem was moving the load of 'total' inside the loop.
+  int count = null ?? total;
+  for (int i = 0; i < count; i++) inc();
+}