Decrease size of arrow in moving dialog from 20px to 16px

Reflecting the updated mocks.

Bug: 1102294
Change-Id: If526eb2754bf4981affb0bb3a2be381f6ac5e143
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352231Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Victor Vianna <victorvianna@google.com>
Cr-Commit-Position: refs/heads/master@{#797242}

chrome/browser/resources/settings/autofill_page/password_move_to_account_dialog.html

@@ -55,7 +55,9 @@
   }
 
   #chevronIcon {
+    height: 16px;
     margin: 0 16px;
+    width: 16px;
   }
 
   :host-context([dir=rtl]) #chevronIcon {