JS IR: mute codegen box tests automatically

compiler/testData/codegen/box/functions/functionExpression/functionExpression.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: JS_IR
 val foo1 = fun Any.(): String {
 return  "239" + this
 }

compiler/testData/codegen/box/functions/functionExpression/functionExpressionWithThisReference.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: JS_IR
 
 fun Int.thisRef1() = fun () = this
 fun Int.thisRef2() = fun (): Int {return this}

compiler/testData/codegen/box/functions/functionExpression/functionLiteralExpression.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: JS_IR
 fun Any.foo1() : ()-> String {
   return { "239" + this }
 }