[CSS Math Functions] Correctly serialize round() root nodes

https://bugs.webkit.org/show_bug.cgi?id=259035
rdar://111984509

Reviewed by Darin Adler.

From the spec https://drafts.csswg.org/css-values-4/#calc-simplification:

> If root is an operator node that’s not one of the calc-operator nodes, and all of its calculation children are numeric values with enough information to compute the operation root represents, return the result of running root’s operation using its children, expressed in the result’s canonical unit.

We now always try to resolve the top-level round() function, e.g. round(up, 2px, 5px) now gives calc(5px) instead of round(up, 2px, 5px).
This is consistent with calc(round(up, 2px, 5px)) being serialized as calc(5px).

* LayoutTests/imported/w3c/web-platform-tests/css/css-values/round-mod-rem-serialize-expected.txt:
* Source/WebCore/css/calc/CSSCalcOperationNode.cpp:
(WebCore::CSSCalcOperationNode::simplifyNode):
* Source/WebCore/css/calc/CSSCalcOperationNode.h:
* Source/WebCore/platform/calc/CalcOperator.h: Remove unnecessary include.

Canonical link: https://commits.webkit.org/265892@main

LayoutTests/imported/w3c/web-platform-tests/css/css-values/round-mod-rem-serialize-expected.txt

@@ -1,6 +1,6 @@
 
-FAIL 'round(1.1,1)' as a specified value should serialize as 'calc(1)'. assert_equals: 'round(1.1,1)' and 'calc(1)' should serialize the same in specified values. expected "calc(1)" but got "round(nearest, 1.1, 1)"
-FAIL 'scale(round(1.1,1))' as a specified value should serialize as 'scale(calc(1))'. assert_equals: 'scale(round(1.1,1))' and 'scale(calc(1))' should serialize the same in specified values. expected "scale(calc(1))" but got "scale(round(nearest, 1.1, 1))"
+PASS 'round(1.1,1)' as a specified value should serialize as 'calc(1)'.
+PASS 'scale(round(1.1,1))' as a specified value should serialize as 'scale(calc(1))'.
 PASS 'round(1.1,1)' as a computed value should serialize as '1'.
 PASS 'scale(round(1.1,1))' as a computed value should serialize as 'matrix(1, 0, 0, 1, 0, 0)'.
 PASS 'mod(1,1)' as a specified value should serialize as 'calc(0)'.

Source/WebCore/css/calc/CSSCalcOperationNode.cpp

@@ -891,7 +891,7 @@ Ref<CSSCalcExpressionNode> CSSCalcOperationNode::simplifyNode(Ref<CSSCalcExpress
             calcOperationNode.hoistChildrenWithOperator(CalcOperator::Multiply);
         }
 
-        if (calcOperationNode.shouldNotPreserveFunction() || calcOperationNode.isCalcProductNode() || calcOperationNode.isCalcSumNode() || (calcOperationNode.shouldPreserveFunction() && depth))
+        if (calcOperationNode.isNonCalcFunction() || calcOperationNode.isCalcProductNode() || calcOperationNode.isCalcSumNode())
             calcOperationNode.combineChildren();
 
         // If only one child remains, return the child (except at the root).
@@ -904,7 +904,7 @@ Ref<CSSCalcExpressionNode> CSSCalcOperationNode::simplifyNode(Ref<CSSCalcExpress
             if (depth)
                 return true;
 
-            if (parent.shouldNotPreserveFunction() && is<CSSCalcPrimitiveValueNode>(parent.children()[0])) {
+            if (parent.isNonCalcFunction() && is<CSSCalcPrimitiveValueNode>(parent.children()[0])) {
                 parent.makeTopLevelCalc();
                 return false;
             }

Source/WebCore/css/calc/CSSCalcOperationNode.h

@@ -72,7 +72,6 @@ class CSSCalcOperationNode final : public CSSCalcExpressionNode {
     bool isHypotNode() const { return m_operator == CalcOperator::Hypot; }
     bool isSqrtNode() const { return m_operator == CalcOperator::Sqrt; }
     bool isPowOrSqrtNode() const { return m_operator == CalcOperator::Pow || isSqrtNode(); }
-    bool shouldPreserveFunction() const { return isRoundOperation(); }
     bool isClampNode() const { return m_operator == CalcOperator::Clamp; }
 
     void hoistChildrenWithOperator(CalcOperator);
@@ -148,7 +147,7 @@ class CSSCalcOperationNode final : public CSSCalcExpressionNode {
     }
 
     void makeTopLevelCalc();
-    bool shouldNotPreserveFunction() const { return isAbsOrSignNode() || isClampNode() || isMinOrMaxNode() || isExpNode() || isHypotNode() || isSteppedNode() || isPowOrSqrtNode() || isInverseTrigNode() || isAtan2Node() || isTrigNode(); }
+    bool isNonCalcFunction() const { return isAbsOrSignNode() || isClampNode() || isMinOrMaxNode() || isExpNode() || isHypotNode() || isRoundOperation() || isSteppedNode() || isPowOrSqrtNode() || isInverseTrigNode() || isAtan2Node() || isTrigNode(); }
     static double evaluateOperator(CalcOperator, const Vector<double>&);
     static Ref<CSSCalcExpressionNode> simplifyNode(Ref<CSSCalcExpressionNode>&&, int depth);
     static Ref<CSSCalcExpressionNode> simplifyRecursive(Ref<CSSCalcExpressionNode>&&, int depth);

Source/WebCore/platform/calc/CalcOperator.h

@@ -25,7 +25,6 @@
 
 #pragma once
 
-#include <cmath>
 #include <wtf/Forward.h>
 #include <wtf/MathExtras.h>