Use accessible get/set arguments for collection element receiver

When generating collection element receiver (such as 'a[i]'), accessible
descriptor for get/set operator should be used.
Otherwise, if the corresponding get/set operator fun is called via an
accessor, its argument types may be different in case of generic fun
specialized with primitive types.

 #KT-20387 Fixed

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

@@ -13454,6 +13454,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             doTest(fileName);
         }
 
+        @TestMetadata("kt20387.kt")
+        public void testKt20387() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/operatorConventions/kt20387.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt4152.kt")
         public void testKt4152() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/operatorConventions/kt4152.kt");