Incorrect comma placement when formatting lambda list

[SolalPirelli]

Version Used: VS 2015 Update 2

Steps to Reproduce:

1. Add using System;
2. Write the following code:

Action a = () => { }, 
       b = () => { };

1. Format the document

Expected Behavior: Nothing changes

Actual Behavior: The comma goes on its own line:

Action a = () => { }
,
       b = () => { };

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Might be related to #7704, another lambda formatting bug I reported.