How do I change the admin toolbar search input box to type=search?
The following hook works. I found it by text searching the project 

function mytheme_preprocess_input(&amp;$variables, $hook) {
 if ($hook == "input" &amp;&amp; $variables['attributes']['id'] == "admin-toolbar-search-input") {
   $variables['attributes']['type']  = "search";
 }
}


It does not solve the icon problem in this case. The icon is in a different DOM element.

The fix to the search icon being over the text was

#admin-toolbar-search-tab input:focus + .icon.is-left {
 display: none;
}