Early Error rules need to be referenced explicitly in PerformEval

[jorendorff]

The proposal contains new early error rules for direct eval inside initializers.

Steps 4-6 of PerformEval should be updated to specify when these rules are actually applied, as those steps already do for new.target and super.

[littledan]

Good point. PRs welcome, if anyone is interested in helping with this specification, cc @xanlpz @caitp