fix starting file newlines

lib/6to5/generation/buffer.js

@@ -66,7 +66,6 @@ Buffer.prototype.removeLast = function (cha) {
 };
 
 Buffer.prototype.newline = function (i, removeLast) {
-  if (!this.buf) return;
   if (this.format.compact) return;
 
   if (_.isBoolean(i)) {
@@ -88,7 +87,10 @@ Buffer.prototype.newline = function (i, removeLast) {
   if (removeLast && this.isLast("\n")) this.removeLast("\n");
 
   this.removeLast(" ");
+
+  // remove whitespace if last character was a newline
   this.buf = this.buf.replace(/\n +$/, "\n");
+
   this._push("\n");
 };