firefox: Update from version 51.0 to 52.0

Release notes [1]:

> Version 52.0, first offered to Release channel users on March 7, 2017
>
> ### New ###
>
> *   Added support for WebAssembly, an emerging standard that brings
>     near-native performance to Web-based games, apps, and software libraries
>     without the use of plugins.
>
> *   Added automatic captive portal detection, for easier access to Wi-Fi
>     hotspots. When accessing the Internet via a captive portal, Firefox will
>     alert users and open the portal login page in a new tab.
>
> *   Implemented the Strict Secure Cookies specification which forbids
>     insecure HTTP sites from setting cookies with the "secure" attribute. In
>     some cases, this will prevent an insecure site from setting a cookie with
>     the same name as an existing "secure" cookie from the same base domain.
>
> *   Added user warnings for non-secure HTTP pages with logins. Firefox now
>     displays a “This connection is not secure” message when users click into
>     the username and password fields on pages that don’t use HTTPS.
>
> *   Enhanced Sync to allow users to send and open tabs from one device to
>     another.
>
> ### Fixed ###
>
> *   Various security fixes
>
> *   Improved text input for third-party keyboard layouts on Windows. This
>     will address some keyboard layouts that
>     *   have chained dead keys
>     *   input two or more characters with a non-printable key or a dead key
>         sequence
>     *   input a character even when a dead key sequence failed to compose a
>         character
>
> ### Changed ###
>
> *   Removed support for Netscape Plugin API (NPAPI) plugins other than Flash.
>     Silverlight, Java, Acrobat and the like are no longer supported.
>
> *   Improved experience for downloads:
>     *   Notification in the toolbar when a download fails
>     *   Quick access to five most recent downloads rather than three
>     *   Larger buttons for canceling and restarting downloads
>
> *   Removed Battery Status API to reduce fingerprinting of users by trackers
>
> *   When not using Direct2D on Windows, Skia is used for content rendering
>
> *   Migrated Firefox users on Windows XP and Windows Vista operating systems
>     to the extended support release (ESR) version of Firefox.
>
> *   Display (but allow users to override) an “Untrusted Connection” error
>     when encountering SHA-1 certificates that chain up to a root
>     certificate included in Mozilla’s CA Certificate Program. (Note:
>     Firefox continues to permit SHA-1 certificates that chain to
>     manually imported root certificates.) Read more about the Mozilla
>     Security Team’s plans to deprecate SHA-1
>
> ### Developer ###
>
> *   Enabled CSS Grid Layout, opening up a world of new possibilities
>     for graphic design
>
> *   Improved security for screen sharing, which now shows a preview
>     and no longer requires a whitelisted domain
>
> *   Redesigned Responsive Design Mode to include device selection,
>     network throttling, and more
>
> ### Unresolved ###
>
> *   Google Hangouts temporarily won't work

Fixes for MFSA 2017-05 [2], also known as [3]:

CVE-2017-5400, CVE-2017-5401, CVE-2017-5402, CVE-2017-5404,
CVE-2017-5407, CVE-2017-5410, CVE-2017-5408, CVE-2017-5405,
CVE-2017-5398.

[1] https://www.mozilla.org/en-US/firefox/52.0/releasenotes/
[2] https://www.mozilla.org/security/known-vulnerabilities/firefox/#firefox52
[3] https://www.mozilla.org/en-US/security/advisories/mfsa2017-05/

firefox.be0

@@ -2,7 +2,7 @@
 
 #export BEE_TMP_TMPDIR=/dev/shm BEE_TMP_BUILDROOT=/dev/shm/bee-root BEE_MAKEFLAGS='-j80'
 
-# BEE_VERSION firefox-51.0-0
+# BEE_VERSION firefox-52.0-0
 
 SRCURL[0]="https://ftp.mozilla.org/pub/firefox/releases/${PKGVERSION}/source/firefox-${PKGVERSION}.source.tar.xz"