Correctly compile unresolved for-in loops.

dart/tests/language/crash_6725_test.dart

Index: dart/tests/language/crash_6725_test.dart
diff --git a/dart/tests/language/crash_6725_test.dart b/dart/tests/language/crash_6725_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..a3861f101b07ad4ceb3a5e9ca6e87613c21c248e
--- /dev/null
+++ b/dart/tests/language/crash_6725_test.dart
@@ -0,0 +1,58 @@
+// 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 a crash in dart2js.
+
+class Fisk {
+  it1(x) {
+    // "key" is unresolved and caused a crash in dart2js.
+    // This is the original example the user reported.
+    for (key in x) {
+      print(key);
+    }
+  }
+
+  it2(x) {
+    // "length" is "intercepted" and handled differently from other
+    // names when an instance of list is observed.
+    for (length in x) {
+      print(length);
+    }
+  }
+
+  it3(x) {
+    // We're pretty sure that there's no "fisk" that is "intercepted".
+    for (fisk in x) {
+      print(fisk);
+    }
+  }
+}
+
+class SubFisk extends Fisk {
+  var key;
+  var length;
+  var fisk;
+}
+
+main() {
+  Fisk f = new SubFisk();
+  if (new DateTime.now() == null) {
+    f = null;
+  }
+
+  f.it1([87, 42]);
+  if (f.key != 42) {
+    throw 'f.key != 42 (${f.key})';
+  }
+
+  f.it2([87, 42]);
+  if (f.length != 42) {
+    throw 'f.length != 42 (${f.length})';
+  }
+
+  f.it3([87, 42]);
+  if (f.fisk != 42) {
+    throw 'f.fisk != 42 (${f.fisk})';
+  }
+}