[breadcrumb] Add 48px tap-target box around the elider drop-down

Position relative the <span elider> child with 48px size, and shift it
into place for centering.

Bug: 1035691
Change-Id: I06e9b6e0e2ed4527902c25265a709682f013a1c8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2094428
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Reviewed-by: Alex Danilo <adanilo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748442}

ui/file_manager/file_manager/foreground/js/ui/breadcrumb.js

@@ -73,13 +73,17 @@ const breadCrumbTemplate = `
     }
 
     span[elider] {
+      --tap-target-shift: -7px;
       -webkit-mask-image: url(../../images/files/ui/menu_ng.svg);
       -webkit-mask-position: center;
       -webkit-mask-repeat: no-repeat;
       background-color: currentColor;
-      height: 36px;
+      height: 48px;
+      margin-top: var(--tap-target-shift);
+      margin-inline-start: var(--tap-target-shift);
+      min-width: 48px;
+      position: relative;
       transform: rotate(90deg);
-      width: 36px;
     }
 
     button[elider] {