[FIR] Remove a strange check from ArgumentInfo.smartCastType

Most probably it was there just to guarantee
that if `argument` is not a smartcast
expression then this property is exactly the
same thing as `originalType`, but it seems
there's not much point in that as none of
the tests fail.

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirTypeCompatibilityHelpers.kt

@@ -88,9 +88,7 @@ internal class ArgumentInfo(
     val originalType: ConeKotlinType,
     val session: FirSession,
 ) {
-    val smartCastType: ConeKotlinType by lazy {
-        if (argument !is FirSmartCastExpression) originalType else userType.fullyExpandedType(session)
-    }
+    val smartCastType: ConeKotlinType by lazy { userType.fullyExpandedType(session) }
 
     val originalTypeInfo get() = originalType.toTypeInfo(session)