LibWeb: Remove CalculatedStyleValue from Angle

...and replace it with AngleOrCalculated.

This has the nice bonus effect of actually handling `calc()` for angles
in a transform function. :^) (Previously we just would have asserted.)

Userland/Libraries/LibWeb/CSS/ComputedValues.h

@@ -105,7 +105,7 @@ public:
     float width { 0 };
 };
 
-using TransformValue = Variant<CSS::Angle, CSS::LengthPercentage, float>;
+using TransformValue = Variant<CSS::AngleOrCalculated, CSS::LengthPercentage, float>;
 
 struct Transformation {
     CSS::TransformFunction function;