Merge pull request #7029 from Snuffleupagus/PDFThumnailView-refactor-canvas-to-image

[PDFThumbnailView] Re-factor the `canvas` to `image` conversion such that we always render to a `canvas`, and then replace it with an `image` once rendering is done

web/pdf_thumbnail_viewer.js

@@ -147,7 +147,8 @@ var PDFThumbnailViewer = (function PDFThumbnailViewerClosure() {
             id: pageNum,
             defaultViewport: viewport.clone(),
             linkService: this.linkService,
-            renderingQueue: this.renderingQueue
+            renderingQueue: this.renderingQueue,
+            disableCanvasToImageConversion: false,
           });
           this.thumbnails.push(thumbnail);
         }