Move the _blockHoist transformer after regenerator

Otherwise wrapped generator functions are hoisted to the top of the
scope even if we want something else to come before them.

lib/6to5/transformation/transform.js

@@ -80,13 +80,12 @@ _.each({
   constants:                 require("./transformers/es6-constants"),
   letScoping:                require("./transformers/es6-let-scoping"),
 
-  _blockHoist:               require("./transformers/_block-hoist"),
-
   generators:                require("./transformers/es6-generators"),
   restParameters:            require("./transformers/es6-rest-parameters"),
 
   protoToAssign:             require("./transformers/optional-proto-to-assign"),
 
+  _blockHoist:               require("./transformers/_block-hoist"),
   _declarations:             require("./transformers/_declarations"),
 
   // wrap up