vm: improve performance of vm.runIn*()

Optimize for common cases in vm.runInContext() and
vm.runInThisContext().

lib/vm.js

@@ -18,21 +18,16 @@ const realRunInContext = Script.prototype.runInContext;
 
 Script.prototype.runInThisContext = function(options) {
   if (options && options.breakOnSigint) {
-    const realRunInThisContextScript = () => {
-      return realRunInThisContext.call(this, options);
-    };
-    return sigintHandlersWrap(realRunInThisContextScript);
+    return sigintHandlersWrap(realRunInThisContext, this, [options]);
   } else {
     return realRunInThisContext.call(this, options);
   }
 };
 
 Script.prototype.runInContext = function(contextifiedSandbox, options) {
   if (options && options.breakOnSigint) {
-    const realRunInContextScript = () => {
-      return realRunInContext.call(this, contextifiedSandbox, options);
-    };
-    return sigintHandlersWrap(realRunInContextScript);
+    return sigintHandlersWrap(realRunInContext, this,
+                              [contextifiedSandbox, options]);
   } else {
     return realRunInContext.call(this, contextifiedSandbox, options);
   }
@@ -83,19 +78,22 @@ exports.isContext = binding.isContext;
 
 // Remove all SIGINT listeners and re-attach them after the wrapped function
 // has executed, so that caught SIGINT are handled by the listeners again.
-function sigintHandlersWrap(fn) {
+function sigintHandlersWrap(fn, thisArg, argsArray) {
   // Using the internal list here to make sure `.once()` wrappers are used,
   // not the original ones.
   let sigintListeners = process._events.SIGINT;
-  if (!Array.isArray(sigintListeners))
-    sigintListeners = sigintListeners ? [sigintListeners] : [];
-  else
+  if (!sigintListeners)
+    return fn.apply(thisArg, argsArray);
+
+  if (Array.isArray(sigintListeners))
     sigintListeners = sigintListeners.slice();
+  else
+    sigintListeners = [sigintListeners];
 
   process.removeAllListeners('SIGINT');
 
   try {
-    return fn();
+    return fn.apply(thisArg, argsArray);
   } finally {
     // Add using the public methods so that the `newListener` handler of
     // process can re-attach the listeners.