src: fix Persistent<> deprecation warning
src: fix Persistent<> deprecation warning

Pass the Isolate to Persistent<Function>::New(). Fixes the following
warning:

  ../../src/node.cc: In function ‘v8::Handle<v8::Value>
  node::UsingDomains(const v8::Arguments&)’:
  ../../src/node.cc:921: warning: ‘New’ is deprecated
  declared at ../../deps/v8/include/v8.h:4438)

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node