Fix some warnings in the core library identified by the static analyzer.

corelib/src/implementation/collections.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * The [Collections] class implements static methods useful when
  * writing a class that implements [Collection] and the [iterator]
  * method.
  */
 class Collections {
-  static void forEach(Iterable<Object> iterable, void f(Object o)) {
+  static void forEach(Iterable iterable, void f(o)) {
     for (final e in iterable) {
       f(e);
     }
   }
 
-  static bool some(Iterable<Object> iterable, bool f(Object o)) {
+  static bool some(Iterable iterable, bool f(o)) {
     for (final e in iterable) {
       if (f(e)) return true;
     }
     return false;
   }
 
-  static bool every(Iterable<Object> iterable, bool f(Object o)) {
+  static bool every(Iterable iterable, bool f(o)) {
     for (final e in iterable) {
       if (!f(e)) return false;
     }
     return true;
   }
 
-  static List<Object> map(Iterable<Object> source,
-                          List<Object> destination,
-                          f(Object o)) {
+  static List map(Iterable source, List destination, f(o)) {
     for (final e in source) {
       destination.add(f(e));
     }
     return destination;
   }
 
-  static List<Object> filter(Iterable<Object> source,
-                             List<Object> destination,
-                             bool f(Object o)) {
+  static List filter(Iterable source, List destination, bool f(o)) {
     for (final e in source) {
       if (f(e)) destination.add(e);
     }
     return destination;
   }
 
-  static bool isEmpty(Iterable<Object> iterable) {
+  static bool isEmpty(Iterable iterable) {
     return !iterable.iterator().hasNext();
   }
 
   // TODO(jjb): visiting list should be an identityHashSet when it exists
 
   /**
    * Returns a string representing the specified collection. If the
    * collection is a [List], the returned string looks like this:
    * [:'[element0, element1, ... elementN]':]. The value returned by its
    * [toString] method is used to represent each element. If the specified
@@ skipping 81 matching lines @@
    * Returns true if the specified collection contains the specified object
    * reference.
    */
   static _containsRef(Collection c, Object ref) {
     for (var e in c) {
       if (e === ref) return true;
     }
     return false;
   }
 }