Show selection without modifying element

[ripla]

Currently selection relies on setting the CSS outline style and adding extra elements to DOM. To avoid the risk of breaking the user's designs the Designer must be able to

• show selection outline without actually modifying anything
• show selection outline without clipping it on the Paper edge

[ripla]

And check the actual CSS definition from Tuomas.

[tanbt]

New design:
https://www.figma.com/file/Y6W4r0LNKZm2QXOEeRtEVVeb/Designer-Panels-Iteration?node-id=608%3A0

CSS from Tuomas:

.selector {
  box-shadow: inset 0 0 1px 1px #4C4C4D,
    inset 0 0 2px 2px rgba(255, 255, 255, 0.7),
    0 0 1px 1px rgba(255, 255, 255, 0.9) ;
}