JS: refactor generation of property callable references

compiler/testData/codegen/box/callableReference/bound/simpleProperty.kt

@@ -1,6 +1,3 @@
-// Enable when callable references to builtin members are supported.
-// IGNORE_BACKEND: JS
-
 fun box(): String {
     val f = "kotlin"::length
     val result = f.get()

compiler/testData/codegen/box/callableReference/property/listOfStringsMapLength.kt

@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 // WITH_RUNTIME
 
 fun box(): String =