Firefox can split a DevTools protocol packet across multiple TCP
reads. The previous reader only checked that some data was available,
then tried to synchronously read the whole length-prefixed packet from
the readiness callback. Once the socket was nonblocking this could make
startup flaky when Firefox opened the inspector.
Buffer incoming bytes instead, and only dispatch messages once a full
length-prefixed JSON payload has arrived. Add a protocol test that sends
a request in two fragments through the real DevTools server.
DevTools server callbacks can outlive the server when deferred work is
queued during connection shutdown. Capture weak pointers for those tasks
and clear socket callbacks while the server is being destroyed so later
actor cleanup cannot touch freed state.
Add protocol coverage that destroys a server with deferred actor cleanup
pending, before adding the style-rule actor path that depends on this.
This is to prepare for an upcoming change where we will need to track
replies to messages by ID. We will be able to add parameters to this
structure without having to edit every single actor subclass header
file.
To aid with debugging web page issues in Ladybird without needing to
implement a fully fledged inspector, we can implement the Firefox
DevTools protocol and use their DevTools. The protocol is described
here:
https://firefox-source-docs.mozilla.org/devtools/backend/protocol.html
This commit contains just enough to connect to Ladybird from a DevTools
client.
