Log Message:
firefox: Update to 87.0

Changelog:
New

  * You'll encounter less website breakage in Private Browsing and Strict
    Enhanced Tracking Protection with SmartBlock, which provides stand-in
    scripts so that websites load properly.

  * To further protect your privacy, our new default HTTP Referrer policy will
    trim path and query string information from referrer headers to prevent
    sites from accidentally leaking sensitive user data.

  * The "Highlight All" feature on Find in Page now displays tick marks
    alongside your scrollbar that correspond to the location of matches found
    on that page.

  * We're proud to announce full support for macOS built-in screen reader,
    VoiceOver.

  * We've added a new locale: Silesian (szl)

Fixed

  * We've fixed several significant accessibility issues:

      + Video controls now have visible focus styling and video and audio
        controls are now keyboard navigable. (Bug 1681007)
      + HTML <meter> is now spoken by screen readers. (Bug 1460378)
      + Firefox now sets a useful initial focus in Add-ons Manager. (Bug 580537
        )
      + Firefox will now fire a name/description change event when
        aria-labelledby/describedby content changes. (Bug 493683)
  * Various security fixes.

Changed

  * To prevent user data loss when filling out forms, we've disabled the
    Backspace key as a navigation shortcut for the back navigation button. To
    re-enable the Backspace keyboard shortcut, you can change the about:config
    preference browser.backspace_action to 0. You can also use the recommended
    Alt + Left arrow (Command + Left arrow on Mac) shortcut instead.
    Firefox keyboard shortcuts

  * We've removed items from the Library menu that weren't used often or have
    other access points in the browser: Synced tabs, Recent highlights, and
    Pocket list.

  * We've simplified the Help menu by reducing redundant items, such as those
    that point to Firefox support pages that can also be accessed via the Get
    Help item.

Enterprise

  * Various bug fixes and new policies have been implemented in the latest
    version of Firefox. You can see more details in the Firefox for Enterprise
    87 Release Notes.

Developer

  * Developer Information
  * We've greatly simplified the Web Developer menu. Go to Application Menu >
    Web Developer > Web Developer Tools to access Inspector, Web Console,
    Debugger, Network Style Error, Performance, Storage Inspector,
    Accessibility, and Application

  * Developers can now use the Page Inspector to simulate prefers-color-scheme
    media queries, without having to change the operating system to light or
    dark mode.

  * Developers can now use the Page Inspector to toggle the :target
    pseudo-class for the currently selected element in addition to the
    pseudo-classes that were previously supported: :hover, :active and :focus,
    :focus-within, :focus-visible, and :visited.

  * There is a number of Page Inspector improvements and bug fixes related to
    inactive CSS rules:

      + The table-layout property is now marked as inactive for non-table
        elements.
      + The scroll-padding properties (shorthand and longhand) are now marked
        as inactive for non-scrollable elements.
      + The text-overflow property was previously incorrectly marked as
        inactive for some overflow values.

Securiy fixes:
#CVE-2021-23981: Texture upload into an unbound backing buffer resulted in an
 out-of-bound read
#CVE-2021-23982: Internal network hosts could have been probed by a malicious
 webpage
#CVE-2021-23983: Transitions for invalid ::marker properties resulted in memory
 corruption
#CVE-2021-23984: Malicious extensions could have spoofed popup information
#CVE-2021-23985: Devtools remote debugging feature could have been enabled
 without indication to the user
#CVE-2021-23986: A malicious extension could have performed credential-less
 same origin policy violations
#CVE-2021-23987: Memory safety bugs fixed in Firefox 87 and Firefox ESR 78.9
#CVE-2021-23988: Memory safety bugs fixed in Firefox 87