Weakable is not thread-safe, so taking a strong reference from a
WeakPtr<Thread> may result in a use-after-free. We don't use this
functionality anywhere anyway, so remove it.
I created this file a couple years ago, but had a copy/pasted copyright
comment from another file, without the authors being changed. It's now
corrected to attribute it to myself, as it should have been already.
- `Threading::Thread` is not polymorphic, there is no need for a virtual
destructor.
- `HTMLAnchorElement::has_download_preference` isn't overridden by
anything.
This warning was introduced in llvm/llvm-project#131188.
When a BackgroundAction completes, it resolves a Promise (stored on the
BackgroundAction object) with a reference to itself. The Promise will
never unset this resolved value, thus it will hold a strong reference to
the BackgroundAction until it is destroyed. But because the Promise is
owned by the BackgroundAction itself, we have a reference cycle, and
neither object can be destroyed.
The only user of BackgroundAction is the ImageDecoder process. The
consequence was that the ImageDecoder process would never release any
image data for successfully decoded images.
To fix this, instead of storing the promise on the class itself, we can
just create it as a local variable and pass it around.
