[FIR] Improve typing to get rid of cast

compiler/fir/cones/src/org/jetbrains/kotlin/fir/symbols/ConeLookupTags.kt

@@ -35,7 +35,7 @@ abstract class ConeTypeAliasLookupTag : ConeClassLikeLookupTag()
 abstract class ConeClassLookupTag : ConeClassLikeLookupTag()
 
 class ConeClassLikeLookupTagImpl(override val classId: ClassId) : ConeClassLikeLookupTag() {
-    var boundSymbol: Pair<*, *>? = null
+    var boundSymbol: Pair<*, ConeClassifierSymbol?>? = null
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/FirSymbolProvider.kt

@@ -23,7 +23,7 @@ abstract class FirSymbolProvider {
         return when (lookupTag) {
             is ConeClassLikeLookupTag -> {
                 (lookupTag as? ConeClassLikeLookupTagImpl)
-                    ?.boundSymbol?.takeIf { it.first === this }?.let { return it.second as ConeClassifierSymbol? }
+                    ?.boundSymbol?.takeIf { it.first === this }?.let { return it.second }
 
                 getClassLikeSymbolByFqName(lookupTag.classId).also {
                     (lookupTag as? ConeClassLikeLookupTagImpl)