document.lastModified: treat invalid dates like unknown ones.

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 4648 matching lines @@
 
 // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-lastmodified
 String Document::lastModified() const {
   DateComponents date;
   bool foundDate = false;
   if (m_frame) {
     if (DocumentLoader* documentLoader = loader()) {
       const AtomicString& httpLastModified =
           documentLoader->response().httpHeaderField(HTTPNames::Last_Modified);
       if (!httpLastModified.isEmpty()) {
-        date.setMillisecondsSinceEpochForDateTime(
-            convertToLocalTime(parseDate(httpLastModified)));
-        foundDate = true;
+        double dateValue = parseDate(httpLastModified);
+        if (!std::isnan(dateValue)) {
+          date.setMillisecondsSinceEpochForDateTime(
+              convertToLocalTime(dateValue));
+          foundDate = true;
+        }
       }
     }
   }
   // FIXME: If this document came from the file system, the HTML5
   // specificiation tells us to read the last modification date from the file
   // system.
   if (!foundDate)
     date.setMillisecondsSinceEpochForDateTime(
         convertToLocalTime(currentTimeMS()));
   return String::format("%02d/%02d/%04d %02d:%02d:%02d", date.month() + 1,
@@ skipping 1906 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->url().getString().utf8().data());
 }
 #endif