LibWeb/CSS: Tell CalculationContext whether to treat numbers as integers

Calc simplification eventually produces a single style-value as its
output. This extra context data will let us know whether a calculated
number should be treated as a `<number>` or an `<integer>`, so that for
example, `z-index: 12` and `z-index: calc(12)` both produce an
`IntegerStyleValue` containing 12.

Libraries/LibWeb/CSS/StyleValues/CalculatedStyleValue.h

@@ -28,6 +28,7 @@ class CalculationNode;
 // Contains the context available at parse-time.
 struct CalculationContext {
     Optional<ValueType> percentages_resolve_as {};
+    bool resolve_numbers_as_integers = false;
 };
 // Contains the context for resolving the calculation.
 struct CalculationResolutionContext {