remove ast option and always return it

README.md

@@ -127,12 +127,15 @@ Compile and run `test.js`.
 ```javascript
 var to5 = require("6to5");
 
-to5.transform("code();", options).code;
+var result = to5.transform("code();", options);
+result.code;
+result.map;
+result.ast;
 
 to5.transformFileSync("filename.js", options).code;
 
 to5.transformFile("filename.js", options, function (err, result) {
-  result.code;
+
 });
 ```
 
@@ -155,10 +158,6 @@ to5.transformFile("filename.js", options, function (err, result) {
   // Default: false
   sourceMap: true,
 
-  // Adds an `ast` property to returned output containing the ast tree used.
-  // Default: false
-  ast: true,
-
   // Filename for use in errors etc.
   // Default: "unknown"
   filename: "filename"

lib/6to5/transform.js

@@ -21,8 +21,7 @@ var transform = module.exports = function (code, opts) {
     whitelist: [],
     sourceMap: false,
     filename:  "unknown",
-    format:    {},
-    ast:       false
+    format:    {}
   });
 
   ensureTransformerNames("blacklist", opts.blacklist);
@@ -59,12 +58,7 @@ transform._run = function (code, tree, opts) {
   }
 
   result.map = result.map || null;
-
-  if (opts.ast) {
-    result.ast = tree;
-  } else {
-    result.ast = null;
-  }
+  result.ast = tree;
 
   return result;
 };