move declaration insertion to a hidden transformer, add tabWidth to recast prettyPrint

lib/6to5/file.js

@@ -22,8 +22,7 @@ File.normaliseOptions = function (opts) {
     blacklist: [],
     whitelist: [],
     sourceMap: false,
-    filename:  "unknown",
-    format:    {}
+    filename:  "unknown"
   });
 
   _.defaults(opts, {
@@ -80,14 +79,6 @@ File.prototype.transform = function (ast) {
     transformer.transform(self);
   });
 
-  var body = ast.program.body;
-
-  _.each(this.declarations, function (declar) {
-    body.unshift(b.variableDeclaration("var", [
-      b.variableDeclarator(declar.uid, declar.node)
-    ]));
-  });
-
   return this.generate();
 };
 
@@ -95,7 +86,10 @@ File.prototype.generate = function () {
   var opts = this.opts;
   var ast  = this.ast;
 
-  var printOpts = {};
+  var printOpts = {
+    tabWidth: 2
+  };
+
   if (opts.sourceMap) {
     printOpts.sourceMapName = opts.sourceMapName;
   }

lib/6to5/transform.js

@@ -39,11 +39,13 @@ transform.test = function (task, assert) {
     var actualCode = actual.code.trim();
     var expectCode = expect.code.trim();
 
+    var printOpts = { tabWidth: 2 };
+
     result     = transform(actualCode, getOpts(actual.filename));
-    actualCode = recast.prettyPrint(result.ast).code;
+    actualCode = recast.prettyPrint(result.ast, printOpts).code;
 
     var expectAst    = util.parse(expect, expectCode);
-    var expectResult = recast.prettyPrint(expectAst);
+    var expectResult = recast.prettyPrint(expectAst, printOpts);
     expectCode       = expectResult.code;
 
     assert.equal(actualCode, expectCode);
@@ -98,7 +100,9 @@ transform.transformers = {
   jsx:                      require("./transformers/jsx"),
 
   _aliasFunctions:          require("./transformers/_alias-functions"),
-  _blockHoist:              require("./transformers/_block-hoist")
+  _blockHoist:              require("./transformers/_block-hoist"),
+  _declarations:            require("./transformers/_declarations"),
+  _useStrict:               require("./transformers/_use-strict")
 };
 
 _.each(transform.transformers, function (transformer, key) {

lib/6to5/transformers/_declarations.js

@@ -0,0 +1,12 @@
+var b = require("recast").types.builders;
+var _ = require("lodash");
+
+module.exports = function (ast, file) {
+  var body = ast.program.body;
+
+  _.each(file.declarations, function (declar) {
+    body.unshift(b.variableDeclaration("var", [
+      b.variableDeclarator(declar.uid, declar.node)
+    ]));
+  });
+};