Fast Buffer safe constructor

lib/buffer.js

@@ -91,6 +91,10 @@ function allocPool () {
 
 
 function Buffer (subject, encoding, legacy, slice_legacy) {
+  if (!(this instanceof Buffer)) {
+    return new Buffer(subject, encoding, legacy, slice_legacy);
+  }
+
   var length, type;
 
   // Are we slicing?