dart2js: reuse stack trace on rethrow

tests/compiler/dart2js_extra/identical_trace_test.dart

Index: tests/compiler/dart2js_extra/identical_trace_test.dart
diff --git a/tests/language/generic_list_checked_test.dart b/tests/compiler/dart2js_extra/identical_trace_test.dart
similarity index 50%
copy from tests/language/generic_list_checked_test.dart
copy to tests/compiler/dart2js_extra/identical_trace_test.dart
index fcff24bc2e8e906492bf4e10e4825d337d199018..8fc86cb97a2d449df51bc8f12781381c577628ce 100644
--- a/tests/language/generic_list_checked_test.dart
+++ b/tests/compiler/dart2js_extra/identical_trace_test.dart
@@ -4,17 +4,20 @@
 
 import 'package:expect/expect.dart';
 
-bool inCheckedMode() {
-  try {
-    int i = 'hest';
-  } catch (e) {
-    return true;
-  }
-  return false;
-}
-
 main() {
-  if (inCheckedMode()) {
-    Expect.throws(() { List<int> t = new List<String>(); });
+  var st1;
+  try {
+    try {
+      throw 'bad';
+    } catch (e, st) {
+      st1 = st;
+      rethrow;
+    }
+    Expect.fail('Exception expected');
+  } catch (e, st2) {
+    Expect.equals(st1, st2);
+    Expect.identical(st1, st2);
+    return;
   }
+  Expect.fail('Exception expected');
 }