Provide mutableSetOf and mutableMapOf

#KT-9663 Fixed

libraries/stdlib/src/kotlin/collections/Maps.kt

@@ -46,6 +46,14 @@ public fun <K, V> mapOf(): Map<K, V> = emptyMap()
 @JvmVersion
 public fun <K, V> mapOf(pair: Pair<K, V>): Map<K, V> = Collections.singletonMap(pair.first, pair.second)
 
+/**
+ * Returns a new [MutableMap] with the specified contents, given as a list of pairs
+ * where the first component is the key and the second is the value.
+ * This map preserves insertion order so iterating through the map's entries will be in the same order.
+ */
+public fun <K, V> mutableMapOf(vararg pairs: Pair<K, V>): MutableMap<K, V>
+        = LinkedHashMap<K, V>(mapCapacity(pairs.size)).apply { putAll(pairs) }
+
 /**
  * Returns a new [HashMap] with the specified contents, given as a list of pairs
  * where the first component is the key and the second is the value.

libraries/stdlib/src/kotlin/collections/Sets.kt

@@ -31,6 +31,8 @@ public fun <T> setOf(vararg elements: T): Set<T> = if (elements.size > 0) elemen
 /** Returns an empty read-only set.  The returned set is serializable (JVM). */
 public fun <T> setOf(): Set<T> = emptySet()
 
+/** Returns a new [MutableSet] with the given elements. */
+public fun <T> mutableSetOf(vararg elements: T): MutableSet<T> = elements.toCollection(LinkedHashSet(mapCapacity(elements.size)))
 
 /** Returns a new [HashSet] with the given elements. */
 public fun <T> hashSetOf(vararg elements: T): HashSet<T> = elements.toCollection(HashSet(mapCapacity(elements.size)))

libraries/stdlib/test/collections/MapTest.kt

@@ -209,6 +209,12 @@ class MapTest {
         assertEquals(2, map["b"])
     }
 
+    @test fun createMutableMap() {
+        val map = mutableMapOf("b" to 1, "c" to 2)
+        map.put("a", 3)
+        assertEquals(listOf("b" to 1, "c" to 2, "a" to 3), map.toList())
+    }
+
     @test fun createLinkedMap() {
         val map = linkedMapOf(Pair("c", 3), Pair("b", 2), Pair("a", 1))
         assertEquals(1, map["a"])

libraries/stdlib/test/collections/SetOperationsTest.kt

@@ -56,7 +56,7 @@ class SetOperationsTest {
         assertEquals(setOf("a", "foo", "beer", "cheese", "bar"), set)
         assertTrue(set !== setOriginal)
 
-        val mset = hashSetOf("a")
+        val mset = mutableSetOf("a")
         mset += "foo"
         mset += listOf("beer", "a")
         mset += arrayOf("cheese", "beer")