[Browsing history] Remove 'beforeunload' to enable caching and prevent duplicate entries
Merge pull request #3449 from Snuffleupagus/history-remove-beforeunload

[Browsing history] Remove 'beforeunload' to enable caching and prevent duplicate entries
Merge branch 'master' of git://github.com/mozilla/pdf.js into presentation-mode-shortcuts
Fixing indentation and rebased to tip