LibWeb: Better align outer max sizes for cells with the specification

The formulas are different between the constrained and non-constrained.

Userland/Libraries/LibWeb/Layout/TableFormattingContext.h

@@ -85,6 +85,8 @@ private:
         CSSPixels min_size { 0 };
         CSSPixels max_size { 0 };
         double percentage_height { 0 };
+        // Store whether the row is constrained: https://www.w3.org/TR/css-tables-3/#constrainedness
+        bool is_constrained { false };
     };
 
     struct Cell {