MD Settings: remove settings-specific border-radius for paper-button

chrome/browser/resources/settings/settings_shared_css.html

 <link rel="import" href="chrome://resources/cr_elements/shared_style_css.html">
 <link rel="import" href="settings_vars_css.html">
 
 <!-- Common styles for Material Design settings. -->
 <dom-module id="settings-shared">
   <template>
     <style include="cr-shared-style">
       /* Included here so we don't have to include "iron-positioning" in every
        * stylesheet. See crbug.com/498405. */
       [hidden] {
@@ skipping 22 matching lines @@
       }
 
       iron-icon[icon='cr:check'],
       iron-icon[icon='settings:done'] {
        --iron-icon-fill-color: var(--google-green-500);
       }
 
       paper-button {
         height: 32px;
         margin: 0;
-        border-radius: 2px;
       }
 
       paper-button[toggles][active] {
         background-color: var(--paper-grey-300);
       }
 
       paper-toggle-button {
         @apply(--settings-actionable);
         height: var(--settings-row-min-height);
         width: 31px;
@@ skipping 315 matching lines @@
       /* Turns the arrow direction downwards, when the bubble is placed above
        * the anchor element */
       .search-bubble-innards.above::after {
         bottom: -5px;
         top: auto;
         transform: rotate(-135deg);
       }
     </style>
   </template>
 </dom-module>