fix regex, allow trailing whitespace

[lukeed]

Allows the example.js to return:

createVNode(2, 'div', null, ['Hello world, ', ['Foo!', 'Bar!']]);

Similarly:

`
        <p>
          This should have
          no new lines in it
          or spaces at start
          and end
        </p>
`

//=> <p> This should have no new lines in it or spaces at start and end </p>