src: fix handle leak in BuildStatsObject()

Create a handle scope before performing a check that creates a handle,
otherwise the handle is leaked into the handle scope of the caller.

PR-URL: nodejs#7711
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

src/node_file.cc

@@ -344,11 +344,11 @@ static void Close(const FunctionCallbackInfo<Value>& args) {
 
 
 Local<Value> BuildStatsObject(Environment* env, const uv_stat_t* s) {
+  EscapableHandleScope handle_scope(env->isolate());
+
   // If you hit this assertion, you forgot to enter the v8::Context first.
   CHECK_EQ(env->context(), env->isolate()->GetCurrentContext());
 
-  EscapableHandleScope handle_scope(env->isolate());
-
   // The code below is very nasty-looking but it prevents a segmentation fault
   // when people run JS code like the snippet below. It's apparently more
   // common than you would expect, several people have reported this crash...