Revert "Add reduce to Collection."

corelib/src/collection.dart

Index: corelib/src/collection.dart
diff --git a/corelib/src/collection.dart b/corelib/src/collection.dart
index b6f656a635194edd69dd55aae5c50e27023e316a..719145acab615314900df2e1bd675bf6b97b6340 100644
--- a/corelib/src/collection.dart
+++ b/corelib/src/collection.dart
@@ -14,28 +14,15 @@ interface Collection<E> extends Iterable<E> {
 
   /**
    * Returns a new collection with the elements [: f(e) :]
-   * for each element [:e:] of this collection.
+   * for each element [e] of this collection. 
    *
    * Note on typing: the return type of f() could be an arbitrary
    * type and consequently the returned collection's
-   * typeis Collection.
+   * typeis Collection.  
    */
   Collection map(f(E element));
 
   /**
-   * Reduce a collection to a single value by iteratively combining each element
-   * of the collection with an existing value using the provided function.
-   * Use [initialValue] as the initial value, and the function [combine] to
-   * create a new value from the previous one and an element.
-   *
-   * Example of calculating the sum of a collection:
-   *
-   *   collection.reduce(0, (prev, element) => prev + element);
-   */
-  Dynamic reduce(Dynamic initialValue,
-                 Dynamic combine(Dynamic previousValue, E element));
-
-  /**
    * Returns a new collection with the elements of this collection
    * that satisfy the predicate [f].
    *