add ganesh checkbox to skfiddle interface

experimental/webtry/templates/template.gyp

 {
   'targets': [
     {
       'configurations': {
         'Debug': { },
         'Release': { }
       },
       'cflags!': [
         '-Werror'
       ],
       'target_name': '{{.Hash}}',
       'type': 'executable',
       'dependencies': [
         'skia_lib.gyp:skia_lib',
         'flags.gyp:flags',
         'tools.gyp:sk_tool_utils'
 
       ],
       'include_dirs': [
         '../include/config',
         '../include/core',
+        '../include/gpu',
         '../tools/flags',
         '../src/core',
       ],
       'conditions': [
         ['skia_os == "mac"', {
                 'defines': ['SK_UNSAFE_BUILD_DESKTOP_ONLY=1']
         }]
       ],
       'sources': [
         '../../cache/src/{{.Hash}}.cpp',
         '../experimental/webtry/main.cpp'
       ],
     }
   ]
 }