Package rpm-build-firefox: Information

- Backport new version to p8 branch

- New release (51.0.1).
- Fixed:
  + CVE-2017-5375: Excessive JIT code allocation allows bypass of ASLR and DEP
  + CVE-2017-5376: Use-after-free in XSL
  + CVE-2017-5377: Memory corruption with transforms to create gradients in Skia
  + CVE-2017-5378: Pointer and frame data leakage of Javascript objects
  + CVE-2017-5379: Use-after-free in Web Animations
  + CVE-2017-5380: Potential use-after-free during DOM manipulations
  + CVE-2017-5390: Insecure communication methods in Developer Tools JSON viewer
  + CVE-2017-5389: WebExtensions can install additional add-ons via modified host requests
  + CVE-2017-5396: Use-after-free with Media Decoder
  + CVE-2017-5381: Certificate Viewer exporting can be used to navigate and save to arbitrary filesystem locations
  + CVE-2017-5382: Feed preview can expose privileged content errors and exceptions
  + CVE-2017-5383: Location bar spoofing with unicode characters
  + CVE-2017-5384: Information disclosure via Proxy Auto-Config (PAC)
  + CVE-2017-5385: Data sent in multipart channels ignores referrer-policy response headers
  + CVE-2017-5386: WebExtensions can use data: protocol to affect other extensions
  + CVE-2017-5394: Android location bar spoofing using fullscreen and JavaScript events
  + CVE-2017-5391: Content about: pages can load privileged about: pages
  + CVE-2017-5392: Weak references using multiple threads on weak proxy objects lead to unsafe memory usage
  + CVE-2017-5393: Remove addons.mozilla.org CDN from whitelist for mozAddonManager
  + CVE-2017-5395: Android location bar spoofing during scrolling
  + CVE-2017-5387: Disclosure of local file existence through TRACK tag error messages
  + CVE-2017-5388: WebRTC can be used to generate a large amount of UDP traffic for DDOS attacks
  + CVE-2017-5374: Memory safety bugs fixed in Firefox 51
  + CVE-2017-5373: Memory safety bugs fixed in Firefox 51 and Firefox ESR 45.7

- Backport new version to p8 branch