[FIR] Fix binding return expression to function

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirAnonymousFunction.kt

@@ -38,6 +38,7 @@ abstract class FirAnonymousFunction : FirPureAbstractElement(), FirFunction<FirA
     abstract override val symbol: FirAnonymousFunctionSymbol
     abstract val label: FirLabel?
     abstract val invocationKind: InvocationKind?
+    abstract val isLambda: Boolean
 
     override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R = visitor.visitAnonymousFunction(this, data)
 

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/impl/FirAnonymousFunctionImpl.kt

@@ -33,7 +33,8 @@ class FirAnonymousFunctionImpl(
     override val session: FirSession,
     override var returnTypeRef: FirTypeRef,
     override var receiverTypeRef: FirTypeRef?,
-    override val symbol: FirAnonymousFunctionSymbol
+    override val symbol: FirAnonymousFunctionSymbol,
+    override val isLambda: Boolean
 ) : FirAnonymousFunction(), FirModifiableFunction<FirAnonymousFunction>, FirAbstractAnnotatedElement {
     override var resolvePhase: FirResolvePhase = FirResolvePhase.DECLARATIONS
     override val annotations: MutableList<FirAnnotationCall> = mutableListOf()

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt

@@ -253,6 +253,7 @@ object NodeConfigurator : AbstractFieldConfigurator() {
             +field(invocationKindType, nullable = true, withReplace = true).apply {
                 isMutable = true
             }
+            +booleanField("isLambda")
         }
 
         typeParameter.configure {