LibWeb/CSS: Rename CalculatedStyleValue -> CSSMathValue

This matches the name in the CSS Typed OM spec. There's quite a lot
still to do to make it match the spec behavior, but this is the first
step.

Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMathFunctions.cpp

@@ -90,7 +90,7 @@ ErrorOr<void> generate_implementation_file(JsonObject& functions_data, Core::Fil
 #include <LibWeb/CSS/MathFunctions.h>
 #include <LibWeb/CSS/Parser/Parser.h>
 #include <LibWeb/CSS/Enums.h>
-#include <LibWeb/CSS/StyleValues/CalculatedStyleValue.h>
+#include <LibWeb/CSS/StyleValues/CSSMathValue.h>
 
 namespace Web::CSS::Parser {
 

Meta/gn/secondary/Userland/Libraries/LibWeb/CSS/StyleValues/BUILD.gn

@@ -11,10 +11,10 @@ source_set("StyleValues") {
     "CSSHSL.cpp",
     "CSSHWB.cpp",
     "CSSKeywordValue.cpp",
+    "CSSMathValue.cpp",
     "CSSOKLCH.cpp",
     "CSSOKLab.cpp",
     "CSSRGB.cpp",
-    "CalculatedStyleValue.cpp",
     "ConicGradientStyleValue.cpp",
     "ContentStyleValue.cpp",
     "DisplayStyleValue.cpp",