Ladybird: Add IPC call for creating a new child tab

This will be used for choosing a navigable that requires opening a new
tab or new window. Such as calls to window.open(), or specific WebDriver
calls.

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -402,6 +402,7 @@ set(SOURCES
     HTML/TraversableNavigable.cpp
     HTML/VideoTrack.cpp
     HTML/VideoTrackList.cpp
+    HTML/WebViewHints.cpp
     HTML/Window.cpp
     HTML/WindowEventHandlers.cpp
     HTML/WindowOrWorkerGlobalScope.cpp