Replace _.each and for-in with for loop in hot paths

lib/6to5/generation/whitespace.js

@@ -11,15 +11,18 @@ Whitespace.prototype.getNewlinesBefore = function (node) {
   var startToken;
   var endToken;
   var tokens = this.tokens;
+  var token;
+
+  for (var i = 0; i < tokens.length; i++) {
+    token = tokens[i];
 
-  _.each(tokens, function (token, i) {
     // this is the token this node starts with
     if (node.start === token.start) {
       startToken = tokens[i - 1];
       endToken = token;
-      return false;
+      break;
     }
-  });
+  }
 
   return this.getNewlinesBetween(startToken, endToken);
 };
@@ -28,15 +31,18 @@ Whitespace.prototype.getNewlinesAfter = function (node) {
   var startToken;
   var endToken;
   var tokens = this.tokens;
+  var token;
+
+  for (var i = 0; i < tokens.length; i++) {
+    token = tokens[i];
 
-  _.each(tokens, function (token, i) {
     // this is the token this node ends with
     if (node.end === token.end) {
       startToken = token;
       endToken = tokens[i + 1];
-      return false;
+      break;
     }
-  });
+  }
 
   if (endToken.type.type === "eof") {
     return 1;

lib/6to5/traverse/index.js

@@ -8,11 +8,13 @@ function traverse(parent, opts, scope) {
   // falsy node
   if (!parent) return;
 
+  var i, j;
+
   // array of nodes
   if (_.isArray(parent)) {
-    _.each(parent, function (node) {
-      traverse(node, opts, scope);
-    });
+    for (i = 0; i < parent.length; i++) {
+      traverse(parent[i], opts, scope);
+    }
     return;
   }
 
@@ -24,7 +26,7 @@ function traverse(parent, opts, scope) {
 
   var stopped = false;
 
-  for (var i in keys) {
+  for (i = 0; i < keys.length; i++) {
     var key = keys[i];
     var nodes = parent[key];
     if (!nodes) continue;
@@ -108,8 +110,8 @@ function traverse(parent, opts, scope) {
     };
 
     if (_.isArray(nodes)) {
-      for (i in nodes) {
-        handle(nodes, i);
+      for (j = 0; j < nodes.length; j++) {
+        handle(nodes, j);
         if (stopped) return;
       }