Improve performance on hot paths by using for loops

lib/6to5/generation/buffer.js

@@ -77,10 +77,9 @@ Buffer.prototype.newline = function (i, removeLast) {
     if (this.endsWith("{\n")) i--;
     if (this.endsWith(util.repeat(i, "\n"))) return;
 
-    var self = this;
-    _.times(i, function () {
-      self.newline(null, removeLast);
-    });
+    for (var j = 0; j < i; j++) {
+      this.newline(null, removeLast);
+    }
     return;
   }
 
@@ -121,7 +120,11 @@ Buffer.prototype.endsWith = function (str) {
 Buffer.prototype.isLast = function (cha, trimRight) {
   var buf = this.buf;
   if (trimRight) buf = util.trimRight(buf);
+  var last = _.last(buf);
 
-  var chars = [].concat(cha);
-  return _.contains(chars, _.last(buf));
+  if (_.isArray(cha)) {
+    return _.contains(cha, last);
+  } else {
+    return cha === last;
+  }
 };

lib/6to5/generation/position.js

@@ -1,33 +1,27 @@
 module.exports = Position;
 
-var _ = require("lodash");
-
 function Position() {
   this.line = 1;
   this.column = 0;
 }
 
 Position.prototype.push = function (str) {
-  var self = this;
-
-  _.each(str, function (cha) {
-    if (cha === "\n") {
-      self.line++;
-      self.column = 0;
+  for (var i = 0; i < str.length; i++) {
+    if (str[i] === "\n") {
+      this.line++;
+      this.column = 0;
     } else {
-      self.column++;
+      this.column++;
+    }
   }
-  });
 };
 
 Position.prototype.unshift = function (str) {
-  var self = this;
-
-  _.each(str, function (cha) {
-    if (cha === "\n") {
-      self.line--;
+  for (var i = 0; i < str.length; i++) {
+    if (str[i] === "\n") {
+      this.line--;
     } else {
-      self.column--;
+      this.column--;
+    }
   }
-  });
 };

lib/6to5/util.js

@@ -188,7 +188,13 @@ exports.codeFrame = function (lines, lineNumber, colNumber) {
 
 exports.repeat = function (width, cha) {
   cha = cha || " ";
-  return new Array(width + 1).join(cha);
+
+  var result = "";
+  for (var i = 0; i < width; i++) {
+    result += cha;
+  }
+
+  return result;
 };
 
 exports.normaliseAst = function (ast, comments, tokens) {