Merge pull request #4932 from nnethercote/cache-pages-earlier

Cache pages at the start of drawing, not the end.

web/page_view.js

@@ -591,8 +591,6 @@ var PageView = function pageView(container, id, scale,
         self.onAfterDraw();
       }
 
-      cache.push(self);
-
       var event = document.createEvent('CustomEvent');
       event.initCustomEvent('pagerender', true, true, {
         pageNumber: pdfPage.pageNumber
@@ -645,6 +643,10 @@ var PageView = function pageView(container, id, scale,
 
     setupAnnotations(div, pdfPage, this.viewport);
     div.setAttribute('data-loaded', true);
+
+    // Add the page to the cache at the start of drawing. That way it can be
+    // evicted from the cache and destroyed even if we pause its rendering.
+    cache.push(this);
   };
 
   this.beforePrint = function pageViewBeforePrint() {