Fixes #2258 -- allow parameter lists in the vertical style.

lib/coffee-script/grammar.js

@@ -127,6 +127,10 @@
         return [$1];
       }), o('ParamList , Param', function() {
         return $1.concat($3);
+      }), o('ParamList OptComma TERMINATOR Param', function() {
+        return $1.concat($4);
+      }), o('ParamList OptComma INDENT ParamList OptComma OUTDENT', function() {
+        return $1.concat($4);
       })
     ],
     Param: [

src/grammar.coffee

@@ -193,6 +193,8 @@ grammar =
     o '',                                       -> []
     o 'Param',                                  -> [$1]
     o 'ParamList , Param',                      -> $1.concat $3
+    o 'ParamList OptComma TERMINATOR Param',    -> $1.concat $4
+    o 'ParamList OptComma INDENT ParamList OptComma OUTDENT', -> $1.concat $4
   ]
 
   # A single parameter in a function definition can be ordinary, or a splat

test/functions.coffee

@@ -193,3 +193,16 @@ test "#1844: bound functions in nested comprehensions causing empty var statemen
 test "#1859: inline function bodies shouldn't modify prior postfix ifs", ->
   list = [1, 2, 3]
   ok true if list.some (x) -> x is 2
+
+test "#2258: allow whitespace-style parameter lists in function definitions", ->
+  func = (
+    a, b, c
+  ) -> c
+  eq func(1, 2, 3), 3
+  
+  func = (
+    a
+    b
+    c
+  ) -> b
+  eq func(1, 2, 3), 2