clang-format: [JS] fix incorrectly collapsed lines after export

statement.

When an exported function would follow a class declaration, it would not
be recognized as a stand-alone function. That would then collapse the
following line with the current one, e.g.

  class C {}
  export function f() {} var x;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@239592 91177308-0d34-0410-b5e6-96231b3b80d8