[JS] Reduce usage of 'js' function in stdlib

Function 'kotlin.js.js' is to be redesigned in JS IR backend,
partially because it is a hard feature to support.

Current implementation is unstable and can cause problems around
 inlining and name generator. Luckily most of its use-cases
can be covered by simpler features like dynamic expressions and
external declarations.

Thus we are reducing it's usage in stdlib to make IR backend more
stable in current state. JavaScript features that can't be covered by dynamic expression are
implemented in 'jsOperators.kt' file respectively for each backend:

 - 'internal inline' function which calls 'js' function inside for current
   pre-IR backend

 - 'internal' function with '_hack' parameters for JS IR backend which will be
   later intinsicified in a compiler

libraries/stdlib/js-ir/runtime/collectionsHacks.kt

@@ -7,13 +7,6 @@ package kotlin.collections
 
 import kotlin.js.*
 
-// Copied from libraries/stdlib/js/src/kotlin/collections/utils.kt
-// Current inliner doesn't rename symbols inside `js` fun
-@Suppress("UNUSED_PARAMETER")
-internal fun deleteProperty(obj: Any, property: Any) {
-    js("delete obj[property]")
-}
-
 internal fun arrayToString(array: Array<*>) = array.joinToString(", ", "[", "]") { toString(it) }
 
 internal fun <T> Array<out T>.contentDeepHashCodeInternal(): Int {