[K/JS] Delete unused internal fillFrom function

As a follow up to the copyOf(newSize) optimization,
the fillFrom function is now unused and can be deleted.

^KT-77646 Fixed

Author: lppedd

libraries/stdlib/js/src/kotlin/kotlin.kt

@@ -32,17 +32,6 @@ public actual fun <T> lazy(mode: LazyThreadSafetyMode, initializer: () -> T): La
 @DeprecatedSinceKotlin(warningSince = "1.9", errorSince = "2.1")
 public actual fun <T> lazy(lock: Any?, initializer: () -> T): Lazy<T> = UnsafeLazyImpl(initializer)
 
-
-internal fun fillFrom(src: dynamic, dst: dynamic): dynamic {
-    val srcLen: Int = src.length
-    val dstLen: Int = dst.length
-    var index: Int = 0
-    val arr = dst.unsafeCast<Array<Any?>>()
-    while (index < srcLen && index < dstLen) arr[index] = src[index++]
-    return dst
-}
-
-
 internal fun arrayCopyResize(source: dynamic, newSize: Int, defaultValue: Any?): dynamic {
     val result = source.slice(0, newSize).unsafeCast<Array<Any?>>()
     copyArrayType(source, result)