Refactor AnnotationImplementationLowering

- Replaced UNDEFINED_OFFSET with SYNTHETIC_OFFSET, it's required by
  Native backend codegen
- Fixed missing overridden symbols
- Enforce adding fakeoverrides for members not overridden by backend
- Support more points for platform customisation

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

@@ -11,9 +11,11 @@ import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
 import org.jetbrains.kotlin.ir.builders.IrBlockBodyBuilder
 import org.jetbrains.kotlin.ir.builders.irCall
 import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrConstructor
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
 import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.isArray
@@ -38,9 +40,8 @@ class JsAnnotationImplementationTransformer(val jsContext: JsIrBackendContext) :
 
     override fun visitClassNew(declaration: IrClass): IrClass {
         if (!declaration.isAnnotationClass) return declaration
-        val properties = declaration.getAnnotationProperties()
         context.irFactory.stageController.unrestrictDeclarationListsAccess {
-            implementEqualsAndHashCode(declaration, declaration, properties, properties)
+            implementGeneratedFunctions(declaration, declaration)
         }
         return declaration
     }
@@ -48,22 +49,17 @@ class JsAnnotationImplementationTransformer(val jsContext: JsIrBackendContext) :
     private val arraysContentEquals: Map<IrType, IrSimpleFunctionSymbol> =
         requireNotNull(jsContext.ir.symbols.arraysContentEquals) { "contentEquals symbols should be defined in JS IR context" }
 
-    override fun generatedEquals(irBuilder: IrBlockBodyBuilder, type: IrType, arg1: IrExpression, arg2: IrExpression): IrExpression {
-        return if (type.isArray() || type.isPrimitiveArray()) {
-            val requiredSymbol =
-                if (type.isPrimitiveArray())
-                    arraysContentEquals[type]
-                else
-                    arraysContentEquals.entries.singleOrNull { (k, _) -> k.isArray() }?.value
-            if (requiredSymbol == null) {
-                error("Can't find an Arrays.contentEquals method for array type ${type.render()}")
-            }
-            irBuilder.irCall(
-                requiredSymbol
-            ).apply {
-                extensionReceiver = arg1
-                putValueArgument(0, arg2)
-            }
-        } else super.generatedEquals(irBuilder, type, arg1, arg2)
+    override fun getArrayContentEqualsSymbol(type: IrType) =
+        when {
+            type.isPrimitiveArray() -> arraysContentEquals[type]
+            else -> arraysContentEquals.entries.singleOrNull { (k, _) -> k.isArray() }?.value
+        } ?: error("Can't find an Arrays.contentEquals method for array type ${type.render()}")
+
+    override fun implementAnnotationPropertiesAndConstructor(
+        implClass: IrClass,
+        annotationClass: IrClass,
+        generatedConstructor: IrConstructor
+    ) {
+        throw IllegalStateException("Should not be called")
     }
 }