Add fromIterable(s) constructors in SplayTreeMap and LinkedHashMap.

sdk/lib/collection/linked_hash_map.dart

Index: sdk/lib/collection/linked_hash_map.dart
diff --git a/sdk/lib/collection/linked_hash_map.dart b/sdk/lib/collection/linked_hash_map.dart
index 3082ce0881a8b99736968e9a37839bb375c80bbb..4ace5890c4429bdac5c96bb092ced35f32709e9e 100644
--- a/sdk/lib/collection/linked_hash_map.dart
+++ b/sdk/lib/collection/linked_hash_map.dart
@@ -21,10 +21,50 @@ part of dart.collection;
 class LinkedHashMap<K, V> implements Map<K, V> {
   external LinkedHashMap();
 
+  /**
+   * Creates a [LinkedHashMap] that contains all key value pairs of [other].
+   */
   factory LinkedHashMap.from(Map<K, V> other) {
     return new LinkedHashMap<K, V>()..addAll(other);
   }
 
+  /**
+   * Creates a [LinkedHashMap] where the keys and values are computed from the
+   * [iterable].
+   *
+   * For each element of the [iterable] this constructor computes a key/value
+   * pair, by applying [key] and [value] respectively.
+   *
+   * The keys of the key/value pairs do not need to be unique. The last
+   * occurrence of a key will simply overwrite any previous value.
+   *
+   * If no values are specified for [key] and [value] the default is the
+   * identity function.
+   */
+  factory LinkedHashMap.fromIterable(Iterable<K> iterable,
+      {K key(element), V value(element)}) {
+    LinkedHashMap<K, V> map = new LinkedHashMap<K, V>();
+    Maps._fillMapWithMappedIterable(map, iterable, key, value);
+    return map;
+  }
+
+  /**
+   * Creates a [LinkedHashMap] associating the given [keys] to [values].
+   *
+   * This constructor iterates over [keys] and [values] and maps each element of
+   * [keys] to the corresponding element of [values].
+   *
+   * If [keys] contains the same object multiple times, the last occurrence
+   * overwrites the previous value.
+   *
+   * It is an error if the two [Iterable]s don't have the same length.
+   */
+  factory LinkedHashMap.fromIterables(Iterable<K> keys, Iterable<V> values) {
+    LinkedHashMap<K, V> map = new LinkedHashMap<K, V>();
+    Maps._fillMapWithIterables(map, keys, values);
+    return map;
+  }
+
   external bool containsKey(Object key);
 
   external bool containsValue(Object value);