Closure compilation: Modify compile_js2.py to not swallow errors.

third_party/closure_compiler/compiler_test.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from ast import literal_eval
 import os
 import tempfile
 import unittest
 
@@ skipping 34 matching lines @@
 
   def _runChecker(self, source_code, needs_output, closure_args=None):
     file_path = "/script.js"
     FileCache._cache[file_path] = source_code
     out_file, out_map = self._createOutFiles()
     args = _COMMON_CLOSURE_ARGS + (closure_args or [])
     if needs_output:
       args.remove("checks_only")
 
     sources = [file_path, _CHROME_SEND_EXTERNS]
-    found_errors, stderr = self._checker.check(sources,
-                                               out_file=out_file,
-                                               closure_args=args)
+    return_code, found_errors, stderr = self._checker.check(
+        sources,
+        out_file=out_file,
+        closure_args=args)
     return found_errors, stderr, out_file, out_map
 
   def _runCheckerTestExpectError(self, source_code, expected_error,
                                  closure_args=None):
     _, stderr, out_file, out_map = self._runChecker(
         source_code, needs_output=False, closure_args=closure_args)
 
     self.assertTrue(expected_error in stderr,
         msg="Expected chunk: \n%s\n\nOutput:\n%s\n" % (
             expected_error, stderr))
@@ skipping 298 matching lines @@
 """
     args = ['warning_level=VERBOSE']
     self._runCheckerTestExpectError(template % '', 'Missing return',
                                     closure_args=args)
     self._runCheckerTestExpectSuccess(template % 'assertNotReached();',
                                       closure_args=args)
 
 
 if __name__ == "__main__":
   unittest.main()