Improve logging around InitHiddenWindow():
- Normalize WinErrorState.
- Simplify access to the OS-cached last-NTSTATUS value.
- Store and clear the last error-state more frequently.
- When ::CreateWindowW() fails, keep enough information to determine
whether a call to ::RegisterClassW() was attempted.
- To rule out user atom table exhaustion, check the capacity and
availability of the user atom table after a call that might have
created a user atom fails.
- To rule out early return from our WndProc, when
::RegisterWindowMessageW() fails, leave the extant value of
sAppShellGeckoMsgId in place.
Differential Revision: https://phabricator.services.mozilla.com/D188307
219ac46b2d