LPS-34903 make portal script textarea wider, higher and resizable

Hey Nate, 

this is the explanation by @sustacek for these changes:

the main advantage I see in this pull is removing the restriction of max-width for the script's textarea. I've also made the default dimensions bigger:

was: 500px wide, 100px high
now: 750px wide, 200px high

Hope you find this usefull,
Josef