node: remove domain nextTick

It's ridiculously cheap to check if process.domain is set. Don't bother
cluttering the code.

src/node.cc

@@ -910,20 +910,12 @@ void SetupDomainUse(const FunctionCallbackInfo<Value>& args) {
   Local<Object> process = PersistentToLocal(node_isolate, process_p);
   Local<Value> tdc_v =
       process->Get(FIXED_ONE_BYTE_STRING(node_isolate, "_tickDomainCallback"));
-  Local<Value> ndt_v =
-      process->Get(FIXED_ONE_BYTE_STRING(node_isolate, "_nextDomainTick"));
   if (!tdc_v->IsFunction()) {
     fprintf(stderr, "process._tickDomainCallback assigned to non-function\n");
     abort();
   }
-  if (!ndt_v->IsFunction()) {
-    fprintf(stderr, "process._nextDomainTick assigned to non-function\n");
-    abort();
-  }
   Local<Function> tdc = tdc_v.As<Function>();
-  Local<Function> ndt = ndt_v.As<Function>();
   process->Set(FIXED_ONE_BYTE_STRING(node_isolate, "_tickCallback"), tdc);
-  process->Set(FIXED_ONE_BYTE_STRING(node_isolate, "nextTick"), ndt);
   process_tickCallback.Reset(node_isolate, tdc);
 }
 

src/node.js

@@ -330,7 +330,6 @@
 
     process.nextTick = nextTick;
     // needs to be accessible from cc land
-    process._nextDomainTick = _nextDomainTick;
     process._tickCallback = _tickCallback;
     process._tickDomainCallback = _tickDomainCallback;
 
@@ -415,16 +414,10 @@
       if (process._exiting)
         return;
 
-      nextTickQueue.push({ callback: callback, domain: null });
-      infoBox[length]++;
-    }
-
-    function _nextDomainTick(callback) {
-      // on the way out, don't bother. it won't get fired anyway.
-      if (process._exiting)
-        return;
-
-      nextTickQueue.push({ callback: callback, domain: process.domain });
+      nextTickQueue.push({
+        callback: callback,
+        domain: process.domain || null
+      });
       infoBox[length]++;
     }
   };