JVM_IR: fix for SingletonReferencesLowering

When replacing an enum entry reference with `this`, you need to take
`this` from the function's `dispatchReceiverParameter`, not the class's
`thisReceiver`. Otherwise the code generator fails to find the reference
among accessible variables.

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

@@ -8177,6 +8177,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/enum/ordinal.kt");
         }
 
+        @TestMetadata("refToThis.kt")
+        public void testRefToThis() throws Exception {
+            runTest("compiler/testData/codegen/box/enum/refToThis.kt");
+        }
+
         @TestMetadata("simple.kt")
         public void testSimple() throws Exception {
             runTest("compiler/testData/codegen/box/enum/simple.kt");

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

@@ -9262,6 +9262,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/enum/ordinal.kt");
         }
 
+        @TestMetadata("refToThis.kt")
+        public void testRefToThis() throws Exception {
+            runTest("compiler/testData/codegen/box/enum/refToThis.kt");
+        }
+
         @TestMetadata("simple.kt")
         public void testSimple() throws Exception {
             runTest("compiler/testData/codegen/box/enum/simple.kt");