Mark dwarf_stack_trace_test as flaky in product mode, due to identical code folding.

tests/standalone/dwarf_stack_trace_test.dart

 // Copyright (c) 2017, 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.
 
 /// VMOptions=--dwarf-stack-traces
 
 import 'package:unittest/unittest.dart';
 import 'dart:io';
 
 bar() {
@@ skipping 53 matching lines @@
     print(result.stdout);
     print(result.stderr);
     throw "'file' failed";
     return;
   }
   if (!result.stdout.contains("shared object")) {
     print("Skipping test because we are not running from a dylib");
     return;
   }
 
-  var frameRegex = new RegExp("pc ([0-9a-z]+)  ([0-9a-zA-Z/\._]+)");
+  var frameRegex = new RegExp("pc ([0-9a-z]+)  ([0-9a-zA-Z/\._-]+)");
   var symbolizedStack = new StringBuffer();
   for (var frameMatch in frameRegex.allMatches(rawStack)) {
     var framePC = frameMatch[1];
     var frameDSO = frameMatch[2];
     print(framePC);
     print(frameDSO);
     result = Process.runSync("addr2line",
                              ["--exe", frameDSO,
                               "--functions",
                               "--inlines",
@@ skipping 13 matching lines @@
   expect(symbolizedStack.toString(),
          stringContainsInOrder(["bar",
                                 "dwarf_stack_trace_test.dart:12",
                                 "foo",
                                 "dwarf_stack_trace_test.dart:17",
                                 "main",
                                 "dwarf_stack_trace_test.dart:23",
                                 "main", // dispatcher
                                 "dwarf_stack_trace_test.dart:20"]));
 }