fix: do not duplicate cmd-line flags on repeated PhantomJS runs

Karma may retry running the same browser instance multiple times in case
something goes wrong with the first run, i.e if the browser process
terminates unexpectedly for some reason. In such cases PhantomJS launcher
would re-add all of its PhantomJS command-line options to the initially
used option list instead of reusing the same one.

index.js

@@ -29,7 +29,7 @@ var PhantomJSBrowser = function (baseBrowserDecorator, config, args, logger) {
   baseBrowserDecorator(this)
 
   var options = args && args.options || config && config.options || {}
-  var flags = args && args.flags || config && config.flags || []
+  var providedFlags = args && args.flags || config && config.flags || []
 
   this._start = function (url) {
     // create the js file that will open karma
@@ -48,6 +48,7 @@ var PhantomJSBrowser = function (baseBrowserDecorator, config, args, logger) {
       }
     })
 
+    var flags = _.clone(providedFlags);
     if (args.debug) {
       flags = flags.concat('--remote-debugger-port=9000')
       flags = flags.concat('--remote-debugger-autorun=yes')