LibWeb: Add a way to ask if a PercentageOr<T> value contains percentages

Values that contain percentages require special treatment in various
parts of layout. Previously we had no way of peeking into calc() values
to see if their expression contains one or more percentages. That's the
bulk of what we're adding here.

Userland/Libraries/LibWeb/CSS/StyleValue.cpp

@@ -2054,4 +2054,51 @@ NonnullRefPtr<StyleValue> BorderRadiusStyleValue::absolutized(Gfx::IntRect const
     return BorderRadiusStyleValue::create(absolutized_horizontal_radius, absolutized_vertical_radius);
 }
 
+bool CalculatedStyleValue::contains_percentage() const
+{
+    return m_expression->contains_percentage();
+}
+
+bool CalculatedStyleValue::CalcSum::contains_percentage() const
+{
+    if (first_calc_product->contains_percentage())
+        return true;
+    for (auto& part : zero_or_more_additional_calc_products) {
+        if (part.contains_percentage())
+            return true;
+    }
+    return false;
+}
+
+bool CalculatedStyleValue::CalcSumPartWithOperator::contains_percentage() const
+{
+    return value->contains_percentage();
+}
+
+bool CalculatedStyleValue::CalcProduct::contains_percentage() const
+{
+    if (first_calc_value.contains_percentage())
+        return true;
+    for (auto& part : zero_or_more_additional_calc_values) {
+        if (part.contains_percentage())
+            return true;
+    }
+    return false;
+}
+
+bool CalculatedStyleValue::CalcProductPartWithOperator::contains_percentage() const
+{
+    return value.visit(
+        [](CalcValue const& value) { return value.contains_percentage(); },
+        [](CalcNumberValue const&) { return false; });
+}
+
+bool CalculatedStyleValue::CalcValue::contains_percentage() const
+{
+    return value.visit(
+        [](Percentage const&) { return true; },
+        [](NonnullOwnPtr<CalcSum> const& sum) { return sum->contains_percentage(); },
+        [](auto const&) { return false; });
+}
+
 }