added extension methods MutableCollection#addAll(Iterable) and MutableCollection#addAll(Iterator) (#KT-4202 fixed)

libraries/stdlib/src/kotlin/MutableCollections.kt

@@ -0,0 +1,15 @@
+package kotlin
+
+/**
+ * Adds all elements of the given *iterator* to this [[MutableCollection]]
+ */
+public fun <T> MutableCollection<T>.addAll(iterator: Iterator<T>): Unit {
+    for (e in iterator) add(e)
+}
+
+/**
+ * Adds all elements of the given *iterable* to this [[MutableCollection]]
+ */
+public fun <T> MutableCollection<T>.addAll(iterable: Iterable<T>): Unit {
+    for (e in iterable) add(e)
+}

libraries/stdlib/test/MutableCollectionsTest.kt

@@ -0,0 +1,29 @@
+package test.collections
+
+import kotlin.test.*
+
+import java.util.*
+
+import org.junit.Test as test
+
+class MutableCollectionTest {
+
+    test fun fromIterable() {
+        val data: Iterable<String> = arrayListOf("foo", "bar")
+
+        val collection = ArrayList<String>()
+        collection.addAll(data)
+
+        assertEquals(data, collection)
+    }
+
+    test fun fromIterator() {
+        val list = arrayListOf("foo", "bar")
+        val collection = ArrayList<String>()
+
+        collection.addAll(list.iterator())
+
+        assertEquals(list, collection)
+    }
+
+}