Keep only a single active stack trace, enables traces for thrown non-exceptions

pkg/dev_compiler/test/browser/language_tests.js

 // Copyright (c) 2015, 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.
 
 define(['dart_sdk', 'async_helper', 'expect', 'unittest', 'is', 'require'],
       function(dart_sdk, async_helper, expect, unittest, is, require) {
   'use strict';
 
   async_helper = async_helper.async_helper;
   let minitest = expect.minitest;
@@ skipping 257 matching lines @@
       'regress_13462_1_test': skip_fail,
       'regress_14105_test': skip_fail,
       'regress_16640_test': skip_fail,
       'regress_18535_test': fail,
       'regress_21795_test': skip_fail,
       'regress_22443_test': skip_fail,
       'regress_22666_test': skip_fail,
       'setter_no_getter_test_01_multi': skip_fail,
       'stack_overflow_stacktrace_test': skip_fail,
       'stack_overflow_test': skip_fail,
-      'stack_trace_test': skip_fail,
-      'stacktrace_rethrow_nonerror_test': skip_fail, // mismatch from Karma's file hash
       'stacktrace_rethrow_error_test_none_multi': skip_fail,
       'stacktrace_rethrow_error_test_withtraceparameter_multi': skip_fail,
       'stacktrace_test': skip_fail,
       'string_interpolate_null_test': skip_fail,
       'super_operator_index3_test': skip_fail,
       'super_operator_index4_test': skip_fail,
       'switch_label2_test': skip_fail,
       'switch_label_test': skip_fail,
       'switch_try_catch_test': skip_fail,
       'sync_generator1_test_none_multi': skip_fail,
@@ skipping 80 matching lines @@
       'map_keys2_test': fail,
       'map_to_string_test': fail,
       'map_from_iterable_test': firefox_fail,
       'nan_infinity_test_01_multi': fail,
       'null_nosuchmethod_test': fail,
       'null_test': fail,
       'num_sign_test': fail,
       'regress_r21715_test': fail,
       'throw_half_surrogate_pair_test_02_multi': fail,
       'splay_tree_from_iterable_test': firefox_fail,
-      'stacktrace_current_test': chrome_fail,
       'string_case_test_01_multi': firefox_fail,
       'string_fromcharcodes_test': skip_timeout,
       'string_operations_with_null_test': fail,
       'symbol_reserved_word_test_06_multi': fail,
       'symbol_reserved_word_test_09_multi': fail,
       'symbol_reserved_word_test_12_multi': fail,
       'throw_half_surrogate_pair_test_01_multi': fail,
       'unicode_test': firefox_fail,
       'uri_parameters_all_test': firefox_fail,
       // TODO(rnystrom): Times out because it tests a huge number of
@@ skipping 451 matching lines @@
 
     for (let action of unittest_tests) {
       try {
         action();
       } catch (e) {
         console.error("Caught error tying to setup test:", e);
       }
     }
   });
 });