Issue 3498 - Improve file mapping / skipping logic

packagerChrome.py

 # coding: utf-8
 
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 import sys
 import os
 import re
 import json
@@ skipping 308 matching lines @@
   params = {
     'type': type,
     'baseDir': baseDir,
     'releaseBuild': releaseBuild,
     'version': version,
     'experimentalAPI': experimentalAPI,
     'devenv': devenv,
     'metadata': metadata,
   }
 
+  mapped = metadata.items('mapping') if metadata.has_section('mapping') else []
   files = Files(getPackageFiles(params), getIgnoredFiles(params),
                 process=lambda path, data: processFile(path, data, params))
 
-  if metadata.has_section('mapping'):
-    files.readMappedFiles(metadata.items('mapping'))
-  files.read(baseDir)
+  files.readMappedFiles(mapped)
+  files.read(baseDir, skip=[opt for opt, _ in mapped])
 
   if metadata.has_section('convert_js'):
     convertJS(params, files)
 
   if metadata.has_section('convert_img'):
     from imageConversion import convertImages
     convertImages(params, files)
 
   if metadata.has_section('preprocess'):
     files.preprocess(
@@ skipping 23 matching lines @@
     files['qunit/index.html'] = createScriptPage(params, 'testIndex.html.tmpl',
                                                  ('general', 'testScripts'))
 
   zipdata = files.zipToString()
   signature = None
   pubkey = None
   if keyFile != None:
     signature = signBinary(zipdata, keyFile)
     pubkey = getPublicKey(keyFile)
   writePackage(outFile, pubkey, signature, zipdata)