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

third_party/closure_compiler/js_minify.py

 #!/usr/bin/env python
 # Copyright 2016 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.
 ''' Javascript minifier using the closure compiler
 
 This minifier strips spaces and comments out of Javascript using the closure
 compiler. It takes the original Javascript on standard input, and outputs
 the minified output on standard output.
 
@@ skipping 10 matching lines @@
 def Minify(source):
   parser = argparse.ArgumentParser()
   parser.add_argument("-c", "--closure_args", nargs=argparse.ZERO_OR_MORE,
                       help="Arguments passed directly to the Closure compiler")
   args = parser.parse_args()
   with tempfile.NamedTemporaryFile(suffix='.js') as t1, \
        tempfile.NamedTemporaryFile(suffix='.js') as t2:
     t1.write(source)
     t1.seek(0)
     checker = Checker()
-    (compile_error, compile_stderr) = checker.check(
+    (_, compile_error, compile_stderr) = checker.check(
         [t1.name],
         out_file=t2.name,
         closure_args=args.closure_args)
     if compile_error:
       print compile_stderr
     t2.seek(0)
     result = t2.read()
     return result
 
 
 if __name__ == '__main__':
   orig_stdout = sys.stdout
   result = ''
   try:
     sys.stdout = sys.stderr
     result = Minify(sys.stdin.read())
   finally:
     sys.stdout = orig_stdout
     print result