Make 'where' lazy.

sdk/lib/collection/collections.dart

Index: sdk/lib/collection/collections.dart
diff --git a/sdk/lib/collection/collections.dart b/sdk/lib/collection/collections.dart
index d0f9c8e865b57a21f6beee7b1a5679c64390046c..71a98d1fb372c669d596ac8feb9796d079d9ee32 100644
--- a/sdk/lib/collection/collections.dart
+++ b/sdk/lib/collection/collections.dart
@@ -44,13 +44,6 @@ class Collections {
     return initialValue;
   }
 
-  static List where(Iterable source, List destination, bool f(o)) {
-    for (final e in source) {
-      if (f(e)) destination.add(e);
-    }
-    return destination;
-  }
-
   static bool isEmpty(Iterable iterable) {
     return !iterable.iterator.moveNext();
   }