WebUI: For cr-dialog, handle Enter keys in paper-inputs.

chrome/browser/resources/settings/certificate_manager_page/certificate_password_encryption_dialog.html

 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
 <link rel="import" href="chrome://resources/html/polymer.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-input/paper-input.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="certificates_browser_proxy.html">
 
 <dom-module id="settings-certificate-password-encryption-dialog">
   <template>
     <style include="settings-shared">
       .password-buttons {
         margin-bottom: 20px;
       }
     </style>
     <dialog is="cr-dialog" id="dialog" close-text="$i18n{close}">
       <div class="title">$i18n{certificateManagerEncryptPasswordTitle}</div>
       <div class="body">
         <div>$i18n{certificateManagerEncryptPasswordDescription}</div>
-        <div class="password-buttons" on-keypress="onKeypress_">
+        <div class="password-buttons">
           <paper-input type="password" value="{{password_}}" id="password"
               label="$i18n{certificateManagerPassword}"
               on-input="validate_"></paper-input>
           <paper-input type="password"
               value="{{confirmPassword_}}" id="confirmPassword"
               label="$i18n{certificateManagerConfirmPassword}"
               on-input="validate_"></paper-input>
         </div>
       </div>
       <div class="button-container">
         <paper-button class="cancel-button" on-tap="onCancelTap_">
           $i18n{cancel}
         </paper-button>
         <paper-button id="ok" class="action-button" on-tap="onOkTap_" disabled>
           $i18n{ok}
         </paper-button>
       </div>
     </dialog>
   </template>
   <script src="certificate_password_encryption_dialog.js"></script>
 </dom-module>