[FIR] Let prefix inc/dec call getter twice for compatibility with K1

#KT-57179 Fixed

js/js.translator/testData/box/expression/misc/KT-740-2.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_K2: JS_IR
 // EXPECTED_REACHABLE_NODES: 1294
 package foo
 
@@ -56,4 +55,4 @@ fun box(): String {
     }
 
     return "OK"
-}
+}