[JS IR] Make JsExport not fail on companion objects (KT-37829)

js/js.translator/testData/typescript-export/declarations/declarations.d.ts

@@ -49,5 +49,11 @@ declare namespace JS_TESTS {
             foo(): number;
         };
         function takesO(o: typeof foo.O): number;
+        class KT_37829 {
+            constructor();
+            readonly Companion: {
+                readonly x: number;
+            };
+        }
     }
 }

js/js.translator/testData/typescript-export/declarations/declarations.kt

@@ -93,4 +93,12 @@ object O {
 }
 
 fun takesO(o: O): Int =
-    O.x + O.foo()
+    O.x + O.foo()
+
+// Test that JsExport with companion object compiles without error.
+// Usage is not supported yet.
+class KT_37829 {
+    companion object {
+        val x = 10
+    }
+}