Add pathops and capture stderr so we can get SkDebugf output.

gyp/webtry.gyp

 # GYP file to build a the webtry sample.
 {
   'targets': [
     {
       'target_name': 'webtry',
       'type': 'executable',
       'include_dirs' : [
         '../src/core',
         '../src/images',
+        '../src/pathops',
         ],
        'sources': [
          '../experimental/webtry/result.cpp',
          '../experimental/webtry/main.cpp',
        ],
        'dependencies': [
          'flags.gyp:flags',
          'skia_lib.gyp:skia_lib',
          'images.gyp:images',
        ],
     },
   ],
 }