Use `DEFAULT_SCALE_VALUE` as default when fetching the `zoom` parameter from `PDFViewerApplication.store` (i.e. `ViewHistory`)

Since the zoom value should be in percent, using `PDFViewer.currentScale` will be wrong by a factor of 100, potentially causing the zoom level of the document to become wrong on load.

web/viewer.js

@@ -790,7 +790,7 @@ var PDFViewerApplication = {
             store.get('exists', false)) {
           var pageNum = store.get('page', '1');
           var zoom = self.preferenceDefaultZoomValue ||
-                     store.get('zoom', self.pdfViewer.currentScale);
+                     store.get('zoom', DEFAULT_SCALE_VALUE);
           var left = store.get('scrollLeft', '0');
           var top = store.get('scrollTop', '0');