Fix build for iOS after "Make nanobench and dm be usable from Chromium build"

gyp/iOSShell.gyp

 #
 {
   'conditions' : [
     [ 'skia_os == "ios"', {
       'targets': [
         {
           'target_name': 'iOSShell',
           'type': 'executable',
           'mac_bundle' : 1,
           'includes': [
@@ skipping 49 matching lines @@
               '$(SDKROOT)/System/Library/Frameworks/MobileCoreServices.framework',
             ],
           },
           'include_dirs' : [
             '../experimental/iOSSampleApp',
             '../experimental/iOSSampleApp/iPad',
             '../experimental/iOSSampleApp/iPhone',
             '../experimental/iOSSampleApp/Shared',
             '../include/utils/ios',
             '../src/views/mac',
+            '../bench',
           ],
           'xcode_settings' : {
             'INFOPLIST_FILE' : '../experimental/iOSShell/iOSShell-Info.plist',
           },
           'xcode_config_file': '../experimental/iOSSampleApp/SkiOSSampleApp-Base.xcconfig',
           'mac_bundle_resources' : [
             '../experimental/iOSSampleApp/iPad/MainWindow_iPad.xib',
             '../experimental/iOSSampleApp/iPhone/MainWindow_iPhone.xib',
           ],
           'conditions' : [
             [ 'skia_gpu == 1', {
               'dependencies': [
                 'gputest.gyp:skgputest',
               ],
             }],
           ],
         },
       ],
     }],
   ]
 }