Remove calls to to-be-deprecated v8::Persistent funcs.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23445021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@220629 0039d316-1c4b-4281-b951-d872f2087c98

net/proxy/proxy_resolver_v8.cc

@@ -342,8 +342,8 @@ class ProxyResolverV8::Context {
   ~Context() {
     v8::Locker locked(isolate_);
 
-    v8_this_.Dispose(isolate_);
-    v8_context_.Dispose(isolate_);
+    v8_this_.Dispose();
+    v8_context_.Dispose();
   }
 
   JSBindings* js_bindings() {