Bug 306874 – Create C++ utilities and declare types required for Swift Back Forward List

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit Process Model

We're creating a Swift version of the Back Forward List IPC message handler.

Swift code can't always directly work with 100% of pre-existing C++ APIs, so we need to introduce a header file which simplifies some types and functions to make them accessible in Swift.

Specifically,
- Make lots of concrete types using statements like
using VectorRefPtrAPIObject = Vector<RefPtr<Object>>;
- Where Swift code would rely on C++ preprocessor macros, we need to do it in C++ instead
- C++ functions to work around a couple of known Swift/C++ interop bugs.

This bug represents the task of adding these functions and concrete types to call from Swift.

[Radar WebKit Bug Importer]

<rdar://problem/169533295>

[EWS]

Committed 306864@main (c4cab0f5e07b): <https://commits.webkit.org/306864@main>

Reviewed commits have been landed. Closing PR #57291 and removing active labels.