Intent to ship: Redeclarable global eval-introduced vars proposal

[Daniel Minor]

As of Firefox 135, I intend to turn the Redeclarable global eval-introduced vars proposal implementation on by default on all platforms. This proposal removes the [[VarNames]] array that 
prevents redeclaring vars that are introduced by running a sloppy direct `eval` at global scope. V8 never implemented this behaviour, so they are already compliant. JavaScriptCore made the change in https://bugs.webkit.org/show_bug.cgi?id=275821.

Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1917139 is the bug to enable.

Standard: https://github.com/tc39/proposal-redeclarable-global-eval-vars