Removed role 'section' from section.

A section is already a section, so there is no need for a role with this name/
Also, no such role exists.
If no role is given explicitly, the default 'region' role is used,
and such a default role should not be set, as browsers do that themselves.

See http://w3c.github.io/html/sections.html#the-section-element

plone/app/portlets/portlets/language.pt

@@ -1,6 +1,6 @@
 <tal:block i18n:domain="plone">
 
-<section class="portlet portletLanguage" role="section">
+<section class="portlet portletLanguage">
     <header class="portletHeader">
         <span class="tile" i18n:translate="box_languages">Languages</span>
     </header>

plone/app/portlets/portlets/login.pt

@@ -1,7 +1,7 @@
 <tal:block condition="view/show"
            i18n:domain="plone">
 
-<section class="portlet portletLogin"  role="section"
+<section class="portlet portletLogin"
     tal:condition="view/available">
 
   <header class="portletHeader">

plone/app/portlets/portlets/news.pt

@@ -2,7 +2,7 @@
       xmlns:tal="http://xml.zope.org/namespaces/tal"
       xmlns:i18n="http://xml.zope.org/namespaces/i18n"
       tal:omit-tag="">
-<section class="portlet portletNews"  role="section"
+<section class="portlet portletNews"
     i18n:domain="plone">
 
   <header class="portletHeader">

plone/app/portlets/portlets/recent.pt

@@ -2,7 +2,7 @@
       xmlns:tal="http://xml.zope.org/namespaces/tal"
       xmlns:i18n="http://xml.zope.org/namespaces/i18n"
       tal:omit-tag="">
-<section class="portlet portletRecent" role="section"
+<section class="portlet portletRecent"
     i18n:domain="plone">
 
     <header class="portletHeader">

plone/app/portlets/portlets/review.pt

@@ -2,7 +2,7 @@
       xmlns:tal="http://xml.zope.org/namespaces/tal"
       xmlns:i18n="http://xml.zope.org/namespaces/i18n"
       tal:omit-tag="">
-<section class="portlet portletWorkflowReview" role="section"
+<section class="portlet portletWorkflowReview"
     i18n:domain="plone">
 
   <header class="portletHeader">

plone/app/portlets/portlets/rss.pt

@@ -2,7 +2,7 @@
       xmlns:tal="http://xml.zope.org/namespaces/tal"
       xmlns:i18n="http://xml.zope.org/namespaces/i18n"
       tal:omit-tag="">
-<section class="portlet portletRss" role="section"
+<section class="portlet portletRss"
     i18n:domain="plone"
     tal:condition="view/enabled">