[IR] Add IrClass.invokeFun helper and use it throughout

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/CallableReferenceLowering.kt

@@ -246,8 +246,7 @@ class CallableReferenceLowering(private val context: CommonBackendContext) : Bod
         }
 
         private fun createInvokeMethod(clazz: IrClass): IrSimpleFunction {
-            val superMethods = superFunctionInterface.declarations.filterIsInstance<IrSimpleFunction>()
+            val superMethod = superFunctionInterface.invokeFun!!
-            val superMethod = superMethods.single { it.name.asString() == "invoke" }
             return clazz.addFunction {
                 setSourceRange(if (isLambda) function else reference)
                 name = superMethod.name
@@ -255,9 +254,7 @@ class CallableReferenceLowering(private val context: CommonBackendContext) : Bod
                 isSuspend = superMethod.isSuspend
                 isOperator = superMethod.isOperator
             }.apply {
-                val secondSuperMethods: List<IrSimpleFunction>? =
+                val secondSuperMethod = secondFunctionInterface?.let { it.invokeFun!! }
-                    secondFunctionInterface?.declarations?.filterIsInstance<IrSimpleFunction>()
-                val secondSuperMethod = secondSuperMethods?.single { it.name.asString() == "invoke" }
 
                 overriddenSymbols = listOfNotNull(
                     superMethod.symbol,

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/InteropCallableReferenceLowering.kt

@@ -218,7 +218,7 @@ class InteropCallableReferenceLowering(val context: JsIrBackendContext) : BodyLo
         lambdaClass: IrClass,
         newDeclarations: MutableList<IrDeclaration>
     ): IrBlockBody {
-        val invokeFun = lambdaClass.declarations.filterIsInstance<IrSimpleFunction>().single { it.name.asString() == "invoke" }
+        val invokeFun = lambdaClass.invokeFun!!
         val superInvokeFun = invokeFun.overriddenSymbols.first { it.owner.isSuspend == invokeFun.isSuspend }.owner
         val lambdaName = Name.identifier("${lambdaClass.name.asString()}\$lambda")
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/misc.kt

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpressionBody
 import org.jetbrains.kotlin.ir.types.getClass
 import org.jetbrains.kotlin.ir.types.isNullableAny
+import org.jetbrains.kotlin.ir.util.invokeFun
 import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
 import org.jetbrains.kotlin.ir.util.isTopLevelDeclaration
 import org.jetbrains.kotlin.name.Name
@@ -116,8 +117,6 @@ fun invokeFunForLambda(call: IrCall) =
     call.extensionReceiver!!
         .type
         .getClass()!!
-        .declarations
+        .invokeFun!!
-        .filterIsInstance<IrSimpleFunction>()
-        .single { it.name.asString() == "invoke" }
 
 fun IrFunction.isInlineFunWithReifiedParameter() = isInline && typeParameters.any { it.isReified }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrUtils.kt

@@ -197,6 +197,9 @@ val IrClassSymbol.fields: Sequence<IrFieldSymbol>
 val IrClass.primaryConstructor: IrConstructor?
     get() = this.declarations.singleOrNull { it is IrConstructor && it.isPrimary } as IrConstructor?
 
+val IrClass.invokeFun: IrSimpleFunction?
+    get() = declarations.filterIsInstance<IrSimpleFunction>().singleOrNull { it.name.asString() == "invoke" }
+
 val IrDeclarationContainer.properties: Sequence<IrProperty>
     get() = declarations.asSequence().filterIsInstance<IrProperty>()