add ensureBlock path method

src/babel/transformation/transformers/es6/arrow-functions.js

@@ -2,7 +2,7 @@ import * as t from "../../../types";
 
 export var visitor = {
   ArrowFunctionExpression(node) {
-    t.ensureBlock(node);
+    this.ensureBlock();
 
     node.expression = false;
     node.type = "FunctionExpression";

src/babel/transformation/transformers/es6/destructuring.js

@@ -18,7 +18,7 @@ export var visitor = {
         t.variableDeclarator(temp)
       ]);
 
-      t.ensureBlock(node);
+      this.ensureBlock();
 
       node.body.body.unshift(t.variableDeclaration("var", [
         t.variableDeclarator(left, temp)
@@ -48,7 +48,7 @@ export var visitor = {
 
     destructuring.init(pattern, key);
 
-    t.ensureBlock(node);
+    this.ensureBlock();
 
     var block = node.body;
     block.body = nodes.concat(block.body);
@@ -84,7 +84,7 @@ export var visitor = {
       destructuring.init(pattern, ref);
     }
 
-    t.ensureBlock(node);
+    this.ensureBlock();
 
     var block = node.body;
     block.body = nodes.concat(block.body);

src/babel/transformation/transformers/es6/for-of.js

@@ -17,7 +17,7 @@ export var visitor = {
     var block  = loop.body;
 
     // ensure that it's a block so we can take all its statements
-    t.ensureBlock(node);
+    this.ensureBlock();
 
     // add the value declaration to the new loop body
     if (declar) {

src/babel/transformation/transformers/es6/parameters.default.js

@@ -27,7 +27,7 @@ export var visitor = {
     if (!hasDefaults(node)) return;
 
     // ensure it's a block, useful for arrow functions
-    t.ensureBlock(node);
+    this.ensureBlock();
 
     var state = {
       iife: false,

src/babel/transformation/transformers/es6/tail-call.js

@@ -150,7 +150,7 @@ class TailCallTransformer {
 
     //
 
-    var body = t.ensureBlock(node).body;
+    var body = this.path.ensureBlock().body;
 
     for (var i = 0; i < body.length; i++) {
       var bodyNode = body[i];

src/babel/traversal/path/conversion.js

@@ -22,3 +22,11 @@ export function toComputedKey(): Object {
 
   return key;
 }
+
+/**
+ * Description
+ */
+
+export function ensureBlock() {
+  return t.ensureBlock(this.node);
+}