Bug 241143

<https://webkit.org/web-inspector/script-blackboxing/> states that
> Script blackboxing is the ability to mark a `<script>` in Web Inspector so that it is ignored by the JavaScript debugger, meaning that any JavaScript execution pauses that would happen in that `<script>` are instead deferred until JavaScript execution has continued outside of that `<script>`.

Based on that, developers will likely expect that breakpoint evaluations fall under the category of "things that the JavaScript debugger does" and therefore should be ignored/deferred.