[JS IR BE] Don't transform toString with extension receiver

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

@@ -6805,6 +6805,11 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             public void testTaggedArrayCopy() throws Exception {
                 runTest("js/js.translator/testData/box/regression/typeChecks/taggedArrayCopy.kt");
             }
+
+            @TestMetadata("toStringExtension.kt")
+            public void testToStringExtension() throws Exception {
+                runTest("js/js.translator/testData/box/regression/typeChecks/toStringExtension.kt");
+            }
         }
     }
 

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

@@ -6840,6 +6840,11 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             public void testTaggedArrayCopy() throws Exception {
                 runTest("js/js.translator/testData/box/regression/typeChecks/taggedArrayCopy.kt");
             }
+
+            @TestMetadata("toStringExtension.kt")
+            public void testToStringExtension() throws Exception {
+                runTest("js/js.translator/testData/box/regression/typeChecks/toStringExtension.kt");
+            }
         }
     }
 

js/js.translator/testData/box/regression/typeChecks/toStringExtension.kt

@@ -0,0 +1,9 @@
+// EXPECTED_REACHABLE_NODES: 1281
+
+package foo
+
+class A
+
+fun A?.toString() = "OK"
+
+fun box() = (null as A?).toString()