If we walked away from a woman every time they give us a sh1t test, then, as Ease said, we would be perpetually masturbating.
This is an opportunity.
I think it's possible to let her know that she is being disrespectful by smiling and saying something like, "Surely you're not bored already." Or depending on the dynamic, you could say something a little ****y like "I guess you're as bored as me." - with a smile of course. Or maybe something playful like, "That reminds me, I need to text my girlfriend to tell her I'll be home late."
Basically something to subtly let her know that you don't like her behavior, but you aren't freaking out about it (getting up and walking out? really?!)
Also, as someone suggested, people frequently use cell phones/texting to deal with awkward silence or "space." Look around in clubs and bars and notice how many girls are standing around texting. Guys too. They're just trying to avoid standing around with their thumb up their ass.
Her motive for texting during an awkward silence on a date may not be low IL or disrespect. It could just be her (admittedly immature) way of dealing with tension.