[cleanup] Remove obsolete CSS.

We're no longer using customized built-in elements, and these particular
lines of CSS have been dead code before, as of the refactoring of the
search input fields as part of the GM3 migration.

Bug: 386453980
Change-Id: Id062ba6ff85df0274910f63591c8064b59f07b1f
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6132878
Auto-Submit: Benedikt Meurer <[email protected]>
Commit-Queue: Changhao Han <[email protected]>
Reviewed-by: Changhao Han <[email protected]>

Author: bmeurer

front_end/ui/legacy/toolbar.css

@@ -468,24 +468,6 @@ select.toolbar-item:focus-visible > * {
   margin-right: 2px;
 }
 
-input[is="history-input"] {
-  margin: 0 1px;
-  border: 1px solid var(--sys-color-neutral-outline);
-  border-radius: 4px;
-  line-height: 16px;
-  padding: 1px 1px 1px 3px;
-  color: var(--sys-color-on-surface);
-}
-
-input[is="history-input"]:focus,
-input[is="history-input"]:not(:placeholder-shown) {
-  border-color: var(--sys-color-state-focus-ring);
-}
-
-input[is="history-input"]:hover:not(:focus) {
-  background-color: var(--sys-color-state-hover-on-subtle);
-}
-
 .toolbar-item.highlight::before {
   content: "";
   position: absolute;