Refactor skia_warnings_as_errors

gyp/angle.gyp

 # ANGLE is the Windows-specific translator from OGL ES 2.0 to D3D 9
 
 {
   'conditions': [
     [ 'skia_angle', {
       'target_defaults': {
         'defines': [
           'NOMINMAX',
         ],
       },
       'variables': {
         'component': 'static_library',
-            'skia_building_angle': 1, # See comment in common_conditions.gypi.
+        'skia_warnings_as_errors': 0,
       },
       'includes': [
         '../third_party/externals/angle/src/build_angle.gypi',
       ],
     }],
   ],
   'targets': [
     {
       'target_name': 'angle',
       'type': 'none',
       'conditions': [
         [ 'skia_angle', {
           'direct_dependent_settings': {
             'include_dirs': [
               '../third_party/externals/angle/include',
             ],
           },
         }],
       ],
     },
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: