[MD History] Fix border radius on history items.

chrome/browser/resources/md_history/history_item.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-checkbox/paper-checkbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://resources/html/icon.html">
 <link rel="import" href="chrome://resources/html/util.html">
 <link rel="import" href="chrome://history/browser_service.html">
 <link rel="import" href="chrome://history/constants.html">
 <link rel="import" href="chrome://history/searched_label.html">
 <link rel="import" href="chrome://history/shared_style.html">
 
 <dom-module id="history-item">
   <template>
     <style include="shared-style">
       :host {
         display: block;
       }
 
       :host(:not([embedded])) #main-container {
         background: #fff;
         border-color: var(--card-border-color);
-        border-radius: 2px;
         border-style: solid;
         border-width: 0 1px;
       }
 
       :host(:not([embedded])) #sizing-container {
         @apply(--card-sizing);
       }
 
       :host([is-first-item]) #main-container {
         margin-top: var(--first-card-padding-top);
       }
 
       :host([is-card-start]) #main-container {
+        border-radius: 2px 2px 0 0;
         border-top-width: 1px;
       }
 
       :host([is-card-end]) #main-container {
         border-bottom-width: 2px;
+        border-radius: 0 0 2px 2px;
         margin-bottom: var(--card-padding-between);
       }
 
+      :host([is-card-start][is-card-end]) #main-container {
+        border-radius: 2px;
+      }
+
       #date-accessed {
         display: none;
       }
 
       :host([is-card-start]) #date-accessed {
         display: flex;
       }
 
       #item-container {
         @apply(--layout-center);
@@ skipping 104 matching lines @@
           </button>
         </div>
         <template is="dom-if" if="[[hasTimeGap]]">
           <div id="time-gap-separator"></div>
         </template>
       </div>
     </div>
   </template>
   <script src="chrome://history/history_item.js"></script>
 </dom-module>