Describe the bug
The Solid border style option is automatically selected when the advanced controls are first opened to set a border on an element, even though no border-style has been assigned yet. This creates a visual bug where the user sees a border while editing the page, but no border is actually displayed on the front.

My suspicion is that the border style control should be loading with the None option selected and there is some kind of JS error tricking the PPB into thinking that a border style is initially set.

To Reproduce
Steps to reproduce the behavior:

1. Open the advanced controls for a new page element, the Solid style option should be selected automatically.
2. Set a border width.
3. The element should now display with a border on the editing screen.
4. Switch to Text mode and check the inline element styles. You should see the border-width style, but the border-style option will be absent.
5. Update the page and view on the front. No border should be displayed on the element.
6. Change the border style to any other option and then back to Solid.
7. Check the page markup again, you should correctly see that solid border style has been added inline.