devtools: remove artificial limit on suggestion box width

This was probably added in the stone ages when displays were 640x480px
For a while this setting was ignored because .suggest-box had
flex-box applied. With 06f5e50 it became
effective again.

My screen has 5120px width, no need to limit suggestion box to 300px.
I think it should be responsibility of the code feeding suggestion box's
items to trim their length reasonably (because that code understands them).
CSS's `overflow:hidden` is not helpful much in pathological cases of long items.
Better to leave suggest-box overgrow screen than hide its content IMO.

@JoelEinbinder ^

resources/unpacked/devtools/front_end/ui/suggestBox.css

@@ -46,7 +46,6 @@
     display: flex;
     flex-direction: column;
     flex: 0 0 auto;
-    max-width: 300px;
 }
 
 .suggest-box-top-spacer {