fix DDC travis bot

pkg/dev_compiler/test-main.js

 var allTestFiles = [];
 var TEST_REGEXP = /(_test|_multi)\.js$/i;
 
 var pathToModule = function(path) {
   return path.replace(/^\/base\//, '').replace(/\.js$/, '');
 };
 
 var testsToSkip = [
   // syntax error in DDC's generated code:
+  '/base/gen/codegen_output/language/assert_message_test.js',
   '/base/gen/codegen_output/language/execute_finally6_test.js',
   '/base/gen/codegen_output/language/switch_label2_test.js',
   '/base/gen/codegen_output/language/infinite_switch_label_test.js',
   '/base/gen/codegen_output/language/switch_label_test.js',
   '/base/gen/codegen_output/language/nested_switch_label_test.js',
   '/base/gen/codegen_output/language/switch_try_catch_test.js',
 
   // module code execution error in DDC's generated code:
   '/base/gen/codegen_output/language/f_bounded_quantification3_test.js',
   '/base/gen/codegen_output/language/regress_16640_test.js',
@@ skipping 39 matching lines @@
     unittest: 'gen/codegen_output/pkg/unittest',
     is: 'node_modules/is_js/is',
   },
 
   // Require all test files before starting tests.
   deps: allTestFiles,
 
   // We have to kickoff jasmine, as it is asynchronous
   callback: window.__karma__.start
 });