Update from chromium https://crrev.com/302282

third_party/libxml/libxml.gyp

Index: third_party/libxml/libxml.gyp
diff --git a/third_party/libxml/libxml.gyp b/third_party/libxml/libxml.gyp
index 3e6f6151576197929d0186964ec4b39eee4c0064..dcc75b90b81bae246ac6c0742a28fb5486a86bb7 100644
--- a/third_party/libxml/libxml.gyp
+++ b/third_party/libxml/libxml.gyp
@@ -51,7 +51,14 @@
               },
             }],
             ['OS == "ios"', {
-              'type': 'none',
+              'type': 'static_library',
+              'sources': [
+                'chromium/libxml_utils.h',
+                'chromium/libxml_utils.cc',
+              ],
+              'include_dirs': [
+                '$(SDKROOT)/usr/include/libxml2',
+              ],
               'all_dependent_settings': {
                 'defines': [
                   'USE_SYSTEM_LIBXML',
@@ -250,6 +257,9 @@
             }],
           ],
         }],
+        ['OS == "ios"', {
+          'toolsets': ['host', 'target'],
+        }],
       ],
     },
   ],