[CRX] Re-initialize initialBookmark after URL rewrite

`PDFViewerApplication` reads from `location.hash` to initialize
`initialBookmark`. But when extensions/chromium/pdfHandler.js prepares
the redirect URL, the reference fragment is encoded instead of bare.
`rewriteUrlClosure` in `chromecom.js` is responsible for decoding the
URL, but that currently runs too late.

To fix this, update `initialBookmark` after rewriting the URL.

This was not a problem in the past because `rewriteUrlClosure` in
`chromecom.js` executed before the initialization of `initialBookmark`.

web/chromecom.js

@@ -42,6 +42,9 @@ if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("CHROME")) {
   }
 
   AppOptions.set("defaultUrl", defaultUrl);
+  // Ensure that PDFViewerApplication.initialBookmark reflects the current hash,
+  // in case the URL rewrite above results in a different hash.
+  PDFViewerApplication.initialBookmark = location.hash.slice(1);
 })();
 
 const ChromeCom = {