LibWeb: Implement “convert a string to a number” for type=time inputs

Author: https://github.com/sideshowbarker
Commit: 8b0f6cb876
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3794
Reviewed-by: https://github.com/tcl3 ✅

Libraries/LibWeb/HTML/HTMLInputElement.h

@@ -278,6 +278,7 @@ private:
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;
 
+    Optional<double> convert_time_string_to_number(StringView input) const;
     Optional<double> convert_string_to_number(StringView input) const;
     String convert_number_to_string(double input) const;