fix($injector): add workaround for fat-arrow stringification in Chrome v50

Closes angular#14487

Author: gkalpak

src/auto/injector.js

@@ -71,7 +71,10 @@ var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
 var $injectorMinErr = minErr('$injector');
 
 function extractArgs(fn) {
-  var fnText = Function.prototype.toString.call(fn).replace(STRIP_COMMENTS, ''),
+  // Support: Chrome 50-51 only
+  // Creating a new string by adding `' '` at the end, to hack around some bug in Chrome v50/51
+  // (See https://github.com/angular/angular.js/issues/14487.)
+  var fnText = Function.prototype.toString.call(fn).replace(STRIP_COMMENTS, '') + ' ',
       args = fnText.match(ARROW_ARG) || fnText.match(FN_ARGS);
   return args;
 }