[JS IR BE] Fix enum entry initialization

Keep helper fields uninitialized. This way thier initialization
would not depend on field initialization order.

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

@@ -343,8 +343,7 @@ class EnumEntryInstancesLowering(val context: JsIrBackendContext) : DeclarationT
             isStatic = true
         }.apply {
             parent = irClass
-            val builder = context.createIrBuilder(irClass.symbol)
-            initializer = builder.run { irExprBody(irImplicitCast(irNull(), type)) }
+            initializer = null
         }
 
         enumEntry.correspondingField = result
@@ -407,8 +406,7 @@ class EnumClassCreateInitializerLowering(val context: JsIrBackendContext) : Decl
         isStatic = true
     }.apply {
         parent = irClass
-        val builder = context.createIrBuilder(irClass.symbol)
-        initializer = builder.run { irExprBody(irBoolean(false)) }
+        initializer = null
     }
 
     private fun createInitEntryInstancesFun(irClass: IrClass, entryInstancesInitializedField: IrField): IrSimpleFunction =

js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java

@@ -6804,6 +6804,11 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/regression"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS_IR, true);
         }
 
+        @TestMetadata("enumEntryInitOrder.kt")
+        public void testEnumEntryInitOrder() throws Exception {
+            runTest("js/js.translator/testData/box/regression/enumEntryInitOrder.kt");
+        }
+
         @TestMetadata("kt2470.kt")
         public void testKt2470() throws Exception {
             runTest("js/js.translator/testData/box/regression/kt2470.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java

@@ -6859,6 +6859,11 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("js/js.translator/testData/box/regression"), Pattern.compile("^([^_](.+))\\.kt$"), null, TargetBackend.JS, true);
         }
 
+        @TestMetadata("enumEntryInitOrder.kt")
+        public void testEnumEntryInitOrder() throws Exception {
+            runTest("js/js.translator/testData/box/regression/enumEntryInitOrder.kt");
+        }
+
         @TestMetadata("kt2470.kt")
         public void testKt2470() throws Exception {
             runTest("js/js.translator/testData/box/regression/kt2470.kt");

js/js.translator/testData/box/regression/enumEntryInitOrder.kt

@@ -0,0 +1,10 @@
+// EXPECTED_REACHABLE_NODES: 1309
+// KJS_WITH_FULL_RUNTIME
+
+enum class E { A, B }
+val x: Any = E.A
+
+fun box(): String {
+    if (x !== E.A) return "Fail"
+    return "OK"
+}