Use LinkedHashMap everywhere to preserve order.

libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt

@@ -184,7 +184,7 @@ fun mapping(): List<GenericFunction> {
         doc { "Returns a map of the elements in original collection grouped by the result of given *toKey* function" }
         typeParam("K")
         returns("Map<K, List<T>>")
-        body { "return groupByTo(HashMap<K, MutableList<T>>(), toKey)" }
+        body { "return groupByTo(LinkedHashMap<K, MutableList<T>>(), toKey)" }
     }
 
     templates add f("groupByTo(map: MutableMap<K, MutableList<T>>, toKey: (T) -> K)") {

libraries/tools/kotlin-stdlib-gen/src/templates/Snapshots.kt

@@ -117,7 +117,7 @@ fun snapshots(): List<GenericFunction> {
         returns("Map<K, T>")
         body {
             """
-            val result = HashMap<K, T>()
+            val result = LinkedHashMap<K, T>()
             for (element in this) {
                 result.put(selector(element), element)
             }