MD Settings: Checks the event target in the language tap event handler

chrome/browser/resources/settings/languages_page/languages_page.html

 <link rel="import" href="chrome://resources/html/assert.html">
 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-collapse/iron-collapse.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-toggle-button/paper-toggle-button.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_expand_button/cr_expand_button.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
@@ skipping 44 matching lines @@
               <a href="$i18n{languagesLearnMoreURL}" target="_blank">
                 $i18n{learnMore}
               </a>
             </span>
             <template is="dom-repeat" items="[[languages.enabled]]">
               <div class$="list-item [[getLanguageItemClass_(
                   item.language.code, prefs.intl.app_locale.value,
                   item.language.supportsUI)]]"
                   on-tap="onLanguageTap_">
 <if expr="not chromeos and not is_win">
                 <div class="start" title="[[item.language.nativeDisplayName]]">

[Dan Beam, 2016/08/11 00:09:51]

can we just move the on-tap to here?

                   [[item.language.displayName]]
                 </div>
 </if>
 <if expr="chromeos or is_win">
                 <div title="[[item.language.nativeDisplayName]]">
                   [[item.language.displayName]]
                 </div>
                 <div class="middle">
                   <iron-icon icon="settings:done"
                       hidden$="[[!isProspectiveUILanguage_(
                           item.language.code, prefs.intl.app_locale.value)]]">
                   </iron-icon>
                 </div>

[Dan Beam, 2016/08/11 00:09:51]

i don't reallly care that much if tapping/clicking the checkbox works.  if you
reallly care, you can wrap with a <div on-tap> around both .middle and .title

[Moe, 2016/08/11 14:41:53]

Let's have a wrapper around title and .middle. Otherwise the language list item
looks entirely actionable but clicks are handled on only a small part of it. I
think that's a bad experience.

 </if>
                 <paper-icon-button id="more-[[item.language.code]]"
-                    icon="cr:more-vert" toggles
+                    icon="cr:more-vert" toggles class="dropdown-trigger"
                     active="{{item.optionsMenuOpened}}">
                 </paper-icon-button>
                 <iron-dropdown opened="{{item.optionsMenuOpened}}"
                     horizontal-align="right" vertical-align="auto">
                   <div class="dropdown-content">
                     <button class="dropdown-item" role="option"
                         on-tap="onMoveUpTap_"
                         hidden="[[isFirstLanguage_(index,
                                                    languages.enabled.*)]]">
                       $i18n{moveUp}
@@ skipping 125 matching lines @@
             associated-control="[[$$('#spellcheck-subpage-trigger')]]"
             page-title="$i18n{editDictionaryPageTitle}">
           <settings-edit-dictionary-page></settings-edit-dictionary-page>
         </settings-subpage>
       </template>
 </if>
     </settings-animated-pages>
   </template>
   <script src="languages_page.js"></script>
 </dom-module>