[K/JS] Remove declarations with @JsExport.Ignore from klib explicit roots

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt

@@ -1359,6 +1359,7 @@ open class IrFileSerializer(
         .build()
 
     open fun backendSpecificExplicitRoot(node: IrAnnotationContainer): Boolean = false
+    open fun backendSpecificExplicitRootExclusion(node: IrAnnotationContainer): Boolean = false
     open fun keepOrderOfProperties(property: IrProperty): Boolean = !property.isConst
     open fun backendSpecificSerializeAllMembers(irClass: IrClass) = false
 
@@ -1376,6 +1377,7 @@ open class IrFileSerializer(
 
         if (backendSpecificExplicitRoot(file)) {
             for (declaration in file.declarations) {
+                if (backendSpecificExplicitRootExclusion(declaration)) continue
                 proto.addExplicitlyExportedToCompiler(serializeIrSymbol(declaration.symbol))
             }
         } else {

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

@@ -39,9 +39,14 @@ class JsIrFileSerializer(
 ) {
     companion object {
         private val JS_EXPORT_FQN = FqName("kotlin.js.JsExport")
+        private val JS_EXPORT_IGNORE_FQN = FqName("kotlin.js.JsExport.Ignore")
     }
 
     override fun backendSpecificExplicitRoot(node: IrAnnotationContainer): Boolean {
-        return node.annotations.hasAnnotation(JS_EXPORT_FQN)
+        return node.annotations.hasAnnotation(JS_EXPORT_FQN) && !backendSpecificExplicitRootExclusion(node)
+    }
+
+    override fun backendSpecificExplicitRootExclusion(node: IrAnnotationContainer): Boolean {
+        return node.annotations.hasAnnotation(JS_EXPORT_IGNORE_FQN)
     }
 }