[FIR] Remove unneeded symbol.fir accesses

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/utils/FirDeclarationUtil.kt

@@ -50,6 +50,10 @@ val FirDeclaration.isNonLocal
 
 val FirCallableDeclaration.isExtension get() = receiverParameter != null
 
+val FirBasedSymbol<*>.isMemberDeclaration: Boolean
+    // Accessing `fir` is ok, because we don't really use it
+    get() = fir is FirMemberDeclaration
+
 val FirBasedSymbol<*>.memberDeclarationNameOrNull: Name?
     // Accessing `fir` is ok, because `nameOrSpecialName` only accesses names
     get() = (fir as? FirMemberDeclaration)?.nameOrSpecialName

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirCallableSymbol.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.mpp.CallableSymbolMarker
 import org.jetbrains.kotlin.name.CallableId
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 
 abstract class FirCallableSymbol<D : FirCallableDeclaration> : FirBasedSymbol<D>(), CallableSymbolMarker {
     abstract val callableId: CallableId
@@ -76,6 +77,10 @@ abstract class FirCallableSymbol<D : FirCallableDeclaration> : FirBasedSymbol<D>
     val name: Name
         get() = callableId.callableName
 
+    val containerSource: DeserializedContainerSource?
+        // This is ok, because containerSource should be set during fir creation
+        get() = fir.containerSource
+
     fun getDeprecation(languageVersionSettings: LanguageVersionSettings): DeprecationsPerUseSite? {
         lazyResolveToPhase(FirResolvePhase.COMPILER_REQUIRED_ANNOTATIONS)
         return fir.deprecationsProvider.getDeprecationsInfo(languageVersionSettings)