LibWeb: Parse and propagate white-space-collapse CSS property

Author: https://github.com/Calme1709
Commit: ea30356fba
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4832
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/gmta ✅

Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPseudoElement.cpp

@@ -436,7 +436,7 @@ bool pseudo_element_supports_property(PseudoElement pseudo_element, PropertyID p
                 // FIXME: text-wrap-mode
                 // FIXME: text-wrap-style
                 append_property("white-space"sv);
-                // FIXME: white-space-collapse
+                append_property("white-space-collapse"sv);
                 // FIXME: white-space-trim
                 append_property("word-break"sv);
                 // FIXME: word-space-transform