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/Percentage.h

@@ -77,6 +77,15 @@ public:
     bool is_percentage() const { return m_value.template has<Percentage>(); }
     bool is_calculated() const { return m_value.template has<NonnullRefPtr<CalculatedStyleValue>>(); }
 
+    bool contains_percentage() const
+    {
+        if (is_percentage())
+            return true;
+        if (is_calculated())
+            return calculated()->contains_percentage();
+        return false;
+    }
+
     Percentage const& percentage() const
     {
         VERIFY(is_percentage());

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; });
+}
+
 }

Userland/Libraries/LibWeb/CSS/StyleValue.h

@@ -609,6 +609,7 @@ public:
         String to_string() const;
         Optional<ResolvedType> resolved_type() const;
         CalculationResult resolve(Layout::Node const*, PercentageBasis const& percentage_basis) const;
+        bool contains_percentage() const;
     };
 
     // This represents that: https://www.w3.org/TR/css-values-3/#calc-syntax
@@ -623,6 +624,8 @@ public:
         String to_string() const;
         Optional<ResolvedType> resolved_type() const;
         CalculationResult resolve(Layout::Node const*, PercentageBasis const& percentage_basis) const;
+
+        bool contains_percentage() const;
     };
 
     struct CalcNumberSum {
@@ -645,6 +648,7 @@ public:
         String to_string() const;
         Optional<ResolvedType> resolved_type() const;
         CalculationResult resolve(Layout::Node const*, PercentageBasis const& percentage_basis) const;
+        bool contains_percentage() const;
     };
 
     struct CalcSumPartWithOperator {
@@ -658,6 +662,7 @@ public:
         String to_string() const;
         Optional<ResolvedType> resolved_type() const;
         CalculationResult resolve(Layout::Node const*, PercentageBasis const& percentage_basis) const;
+        bool contains_percentage() const;
     };
 
     struct CalcProductPartWithOperator {
@@ -667,6 +672,8 @@ public:
         String to_string() const;
         Optional<ResolvedType> resolved_type() const;
         CalculationResult resolve(Layout::Node const*, PercentageBasis const& percentage_basis) const;
+
+        bool contains_percentage() const;
     };
 
     struct CalcNumberProduct {
@@ -734,6 +741,8 @@ public:
     Optional<float> resolve_number();
     Optional<i64> resolve_integer();
 
+    bool contains_percentage() const;
+
 private:
     explicit CalculatedStyleValue(NonnullOwnPtr<CalcSum> calc_sum, ResolvedType resolved_type)
         : StyleValue(Type::Calculated)