Re-apply formal argument, arrow function parsing refactors

src/messages.js

Index: src/messages.js
diff --git a/src/messages.js b/src/messages.js
index 5d8ff65627a1dafa79bbf5cd265abe41a9d9861d..ed6601fe38a928870ca9fbf2b96ba4ae993c44d0 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -181,7 +181,11 @@ var kMessages = {
   array_not_subclassable:        ["Subclassing Arrays is not currently supported."],
   for_in_loop_initializer:       ["for-in loop variable declaration may not have an initializer."],
   for_of_loop_initializer:       ["for-of loop variable declaration may not have an initializer."],
-  for_inof_loop_multi_bindings:  ["Invalid left-hand side in ", "%0", " loop: Must have a single binding."]
+  for_inof_loop_multi_bindings:  ["Invalid left-hand side in ", "%0", " loop: Must have a single binding."],
+  bad_getter_arity:              ["Getter must not have any formal parameters."],
+  bad_setter_arity:              ["Setter must have exactly one formal parameter."],
+  this_formal_parameter:         ["'this' is not a valid formal parameter name"],
+  duplicate_arrow_function_formal_parameter: ["Arrow function may not have duplicate parameter names"]
 };