Open headers and blocks if they are closed.

Because they can not be opened with javascript for now.
Fixes #355

www/js/app.js

@@ -932,6 +932,17 @@ define(['jquery', 'zimArchiveLoader', 'util', 'uiUtil', 'cookies','abstractFiles
         }
 
         function loadCSSJQuery() {
+            // Ensure all sections are open for clients that lack JavaScript support, or that have some restrictive CSP [kiwix-js #355].
+            // This is needed only for some versions of ZIM files generated by mwoffliner (at least in early 2018), where the article sections are closed by default on small screens.
+            // These sections can be opened by clicking on them, but this is done with some javascript.
+            // The code below is a workaround, a better fix is tracked on [mwoffliner #324]
+            var iframe = document.getElementById('articleContent').contentDocument;
+            var collapsedBlocks = iframe.querySelectorAll('.collapsible-block:not(.open-block), .collapsible-heading:not(.open-block)');
+            // Using decrementing loop to optimize performance : see https://stackoverflow.com/questions/3520688 
+            for (var i = collapsedBlocks.length; i--;) {
+                collapsedBlocks[i].classList.add('open-block');
+            }
+            
             $('#articleContent').contents().find('link[rel=stylesheet]').each(function() {
                 var link = $(this);
                 // We try to find its name (from an absolute or relative URL)