Always split collections and argument lists with trailing commas.

test/regression/0200/0223.stmt

 >>>
 Foo barBaz() => new Quux({
   'alpha.beta.gamma': [
     new Zuul({'yarrr': Abracadabra.OPEN_SESAME,}, {
       'toil': {'trouble': {'fireBurn': {'cauldronBubble': EYE_OF_NEWT,}}}
     })
   ]
 });
 <<<
 Foo barBaz() => new Quux({
       'alpha.beta.gamma': [
         new Zuul({
           'yarrr': Abracadabra.OPEN_SESAME,
         }, {
           'toil': {
             'trouble': {
-              'fireBurn': {'cauldronBubble': EYE_OF_NEWT,}
+              'fireBurn': {
+                'cauldronBubble': EYE_OF_NEWT,
+              }
             }
           }
         })
       ]
     });