Bank of America crashes on launch when using ServiceExtensions XPC se…

…rvices

https://bugs.webkit.org/show_bug.cgi?id=267124
rdar://119993070

Reviewed by Wenson Hsieh.

Fix crash on launch of WebKit processes, if the process launcher is deleted early. Create the XPC connection
after we have verified that we have a process launcher, otherwise we will get a XPC misuse crash because
the connection will be deleted in a resumed state.

* Source/WebKit/UIProcess/Launcher/cocoa/ProcessLauncherCocoa.mm:
(WebKit::ProcessLauncher::launchProcess):

Canonical link: https://commits.webkit.org/272686@main

Source/WebKit/UIProcess/Launcher/cocoa/ProcessLauncherCocoa.mm

@@ -171,13 +171,12 @@ static void launchWithExtensionKit(ProcessLauncher& processLauncher, ProcessLaun
             return;
         }
         callOnMainRunLoop([weakProcessLauncher = weakProcessLauncher, name = name, process = RetainPtr<_SEExtensionProcess>(process)] {
-            auto connection = [process makeLibXPCConnectionError:nil];
             auto launcher = weakProcessLauncher.get();
             if (!launcher) {
                 [process invalidate];
                 return;
             }
-            launcher->m_xpcConnection = connection;
+            launcher->m_xpcConnection = [process makeLibXPCConnectionError:nil];
             launcher->m_process = WTFMove(process);
             launcher->finishLaunchingProcess(name.characters());
         });