Skip expect declaration

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrDeclarationToJsTransformer.kt

@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.js.backend.ast.JsVars
 class IrDeclarationToJsTransformer : BaseIrElementToJsNodeTransformer<JsStatement, JsGenerationContext> {
 
     override fun visitSimpleFunction(declaration: IrSimpleFunction, context: JsGenerationContext): JsStatement {
+        if (declaration.descriptor.isExpect) return JsEmpty // TODO: fix it in Psi2Ir
         return declaration.accept(IrFunctionToJsTransformer(), context).makeStmt()
     }
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt

@@ -28,6 +28,8 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
 
     fun generate(): JsStatement {
 
+        if (irClass.descriptor.isExpect) return JsEmpty // TODO: fix it in Psi2Ir
+
         maybeGeneratePrimaryConstructor()
         val transformer = IrDeclarationToJsTransformer()