Typing fixes to eliminate casts/dcalls

test/generated_sdk/lib/collection/hash_map.dart

 // Copyright (c) 2013, 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.
 
 part of dart.collection;
 
 /** Default function for equality comparison in customized HashMaps */
-bool _defaultEquals(a, b) => a == b;
+bool _defaultEquals(Object a, Object b) => a == b;
 /** Default function for hash-code computation in customized HashMaps */
-int _defaultHashCode(a) => a.hashCode;
+int _defaultHashCode(Object a) => a.hashCode;
 
 /** Type of custom equality function */
 typedef bool _Equality<K>(K a, K b);
 /** Type of custom hash code function. */
 typedef int _Hasher<K>(K object);
 
 /**
  * A hash-table based implementation of [Map].
  *
  * The keys of a `HashMap` must have consistent [Object.operator==]
@@ skipping 40 matching lines @@
    * of an object, or what it compares equal to, should not change while the
    * object is in the table. If it does change, the result is unpredictable.
    *
    * If you supply one of [equals] and [hashCode],
    * you should generally also to supply the other.
    * An example would be using [identical] and [identityHashCode],
    * which is equivalent to using the shorthand [HashMap.identity]).
    */
   factory HashMap({ bool equals(K key1, K key2),
                     int hashCode(K key),
-                    bool isValidKey(potentialKey) }) {
+                    bool isValidKey(Object potentialKey) }) {
     if (isValidKey == null) {
       if (hashCode == null) {
         if (equals == null) {
           return new _HashMap<K, V>();
         }
         hashCode = _defaultHashCode;
       } else {
         if (identical(identityHashCode, hashCode) &&
             identical(identical, equals)) {
           return new _IdentityHashMap<K, V>();
@@ skipping 61 matching lines @@
    * overwrites the previous value.
    *
    * It is an error if the two [Iterable]s don't have the same length.
    */
   factory HashMap.fromIterables(Iterable<K> keys, Iterable<V> values) {
     HashMap<K, V> map = new HashMap<K, V>();
     Maps._fillMapWithIterables(map, keys, values);
     return map;
   }
 }