clang-format: [JS] Support comments in dict literals.

Before:
  var stuff = {
    // comment for update
    update : false,
             // comment for update
    modules : false,
              // comment for update
    tasks : false
  };

After:
  var stuff = {
    // comment for update
    update : false,
    // comment for update
    modules : false,
    // comment for update
    tasks : false
  };

llvm-svn: 217157