skia: Add support for ANGLE on linux

gyp/common_conditions.gypi

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
@@ skipping 232 matching lines @@
                 ],
               }],
               [ 'skia_arch_type == "x86" and not skia_android_framework', {
                 'cflags': [
                   '-m32',
                 ],
                 'ldflags': [
                   '-m32',
                 ],
               }],
+              [ 'skia_angle == 1' , {
+                'cflags!': [
+                  '-fstrict-aliasing',
+                ],
+                'cflags_cc!': [
+                  '-Wnon-virtual-dtor',
+                ],
+                'cflags_cc': [
+                  '-Wno-unknown-pragmas',
+                ],
+              }],
             ],
           }],
           [ 'skia_warnings_as_errors', {
             'cflags': [
               '-Werror',
             ],
           }],
           # For profiling; reveals some costs, exaggerates others (e.g. trivial setters & getters).
           [ 'skia_disable_inlining', {
             'cflags': [
@@ skipping 358 matching lines @@
     [ 'sknx_no_simd', {
       'defines': [ 'SKNX_NO_SIMD' ],
     }],
 
   ], # end 'conditions'
   # The Xcode SYMROOT must be at the root. See build/common.gypi in chromium for more details
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }