Revert "Add "contains" method to Collection."

tests/corelib/collection_to_string_test.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.
 
 /**
- * Tests for the toString methods on collections and maps.
+ * Tests for the toString methods on collections (including maps).
  */
 
 #library('collection_to_string');
 #import('dart:math', prefix: 'Math');
 
 // TODO(jjb): seed random number generator when API allows it
 
 const int NUM_TESTS = 300;
 const int MAX_COLLECTION_SIZE = 7;
 
@@ skipping 98 matching lines @@
  * If exact is true, the returned collections will not be, and will not contain
  * a collection with ill-defined iteration order (i.e., a HashSet or HashMap).
  */
 Object randomCollection(int size, StringBuffer stringRep, {bool exact}) {
   return randomCollectionHelper(size, exact, stringRep, []);
 }
 
 /**
  * Return a random collection (or map) of the specified size, placing its
  * string representation into the given string buffer. The beingMade
- * parameter is a list of collections currently under construction, i.e.,
+ * parameter is a list of collections currently under construction, i.e., 
  * candidates for recursive references.
  *
  * If exact is true, the returned collections will not be, and will not contain
  * a collection with ill-defined iteration order (i.e., a HashSet or HashMap).
  */
 Object randomCollectionHelper(int size, bool exact, StringBuffer stringRep,
     List beingMade) {
   double interfaceFrac = rand.nextDouble();
 
   if (exact) {
@@ skipping 13 matching lines @@
       return randomSet(size, exact, stringRep, beingMade);
     } else {
       return randomMap(size, exact, stringRep, beingMade);
     }
   }
 }
 
 /**
  * Return a random List of the specified size, placing its string
  * representation into the given string buffer. The beingMade
- * parameter is a list of collections currently under construction, i.e.,
+ * parameter is a list of collections currently under construction, i.e., 
  * candidates for recursive references.
  *
  * If exact is true, the returned collections will not be, and will not contain
  * a collection with ill-defined iteration order (i.e., a HashSet or HashMap).
  */
 List randomList(int size, bool exact, StringBuffer stringRep, List beingMade) {
   return populateRandomCollection(size, exact, stringRep, beingMade, []);
 }
 
 /**
@@ skipping 124 matching lines @@
 bool randomBool() {
   return rand.nextBool();
 }
 
 /** Returns the alphabetized characters in a string. */
 String alphagram(String s) {
   List<int> chars = s.charCodes();
   chars.sort((int a, int b) => a - b);
   return new String.fromCharCodes(chars);
 }