[FIR] Introduce & use FirTypeRef.coneType

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirAnnotationUtils.kt

@@ -15,12 +15,12 @@ import org.jetbrains.kotlin.fir.resolve.toSymbol
 import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
 import org.jetbrains.kotlin.fir.types.ConeClassLikeType
-import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.Name
 
 private fun FirAnnotationCall.toAnnotationLookupTag(): ConeClassLikeLookupTag =
-    ((annotationTypeRef as FirResolvedTypeRef).type as ConeClassLikeType).lookupTag
+    (annotationTypeRef.coneType as ConeClassLikeType).lookupTag
 
 internal fun FirAnnotationCall.toAnnotationClassId(): ClassId =
     toAnnotationLookupTag().classId

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt

@@ -488,13 +488,11 @@ class FirElementSerializer private constructor(
         }
 
         if (parameter.isVararg) {
-            val varargElementType = parameter.returnTypeRef.coneTypeSafe<ConeKotlinType>()?.varargElementType(session)
-            if (varargElementType != null) {
-                if (useTypeTable()) {
-                    builder.varargElementTypeId = typeId(varargElementType)
-                } else {
-                    builder.setVarargElementType(typeProto(varargElementType))
-                }
+            val varargElementType = parameter.returnTypeRef.coneType.varargElementType(session)
+            if (useTypeTable()) {
+                builder.varargElementTypeId = typeId(varargElementType)
+            } else {
+                builder.setVarargElementType(typeProto(varargElementType))
             }
         }
 
@@ -544,7 +542,7 @@ class FirElementSerializer private constructor(
     fun typeId(type: ConeKotlinType): Int = typeTable[typeProto(type)]
 
     internal fun typeProto(typeRef: FirTypeRef): ProtoBuf.Type.Builder {
-        return typeProto((typeRef as FirResolvedTypeRef).type)
+        return typeProto(typeRef.coneType)
     }
 
     internal fun typeProto(type: ConeKotlinType): ProtoBuf.Type.Builder {