fix(middleware): does not work with mootools

Change karma.js to use a forEach loop over files.included
Because mootools adds functions to the array prototype,
the use of for..in will get more than the array elements.

lib/middleware/karma.js

@@ -174,8 +174,7 @@ var createKarmaMiddleware = function (
 
           var scriptTags = []
           var scriptUrls = []
-          for (var i in files.included) {
-            var file = files.included[i]
+          files.included.forEach(function (file) {
             var filePath = file.path
             var fileExt = path.extname(filePath)
 
@@ -191,12 +190,12 @@ var createKarmaMiddleware = function (
 
             if (fileExt === '.css') {
               scriptTags.push(util.format(LINK_TAG_CSS, filePath))
-              continue
+              return
             }
 
             if (fileExt === '.html') {
               scriptTags.push(util.format(LINK_TAG_HTML, filePath))
-              continue
+              return
             }
 
             // The script tag to be placed
@@ -209,7 +208,7 @@ var createKarmaMiddleware = function (
 
             var crossOriginAttribute = includeCrossOriginAttribute ? CROSSORIGIN_ATTRIBUTE : ''
             scriptTags.push(util.format(SCRIPT_TAG, scriptType, filePath, crossOriginAttribute))
-          }
+          })
 
           // TODO(vojta): don't compute if it's not in the template
           var mappings = files.served.map(function (file) {