[JS IR] Emit original names for local vars to sourcemaps

#KT-35655 Fixed

compiler/testData/debug/localVariables/receiverMangling/simple.kt

@@ -7,7 +7,12 @@ fun box() {
     "OK".foo(42)
 }
 
-// EXPECTATIONS
+// EXPECTATIONS JVM JVM_IR
 // test.kt:7 box:
 // test.kt:4 foo: $this$foo:java.lang.String="OK":java.lang.String, a:int=42:int
-// test.kt:8 box:
+// test.kt:8 box:
+
+// EXPECTATIONS JS_IR
+// test.kt:7 box:
+// test.kt:4 foo: <this>="OK":kotlin.String, a=42:number
+// test.kt:8 box: