cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/collection/hash_map.dart

Index: test/generated_sdk/lib/collection/hash_map.dart
diff --git a/test/generated_sdk/lib/collection/hash_map.dart b/test/generated_sdk/lib/collection/hash_map.dart
index 591686d245ce90a8df5dc008c73a7ccf34c39bf2..5ee7926124ca4952040f83261832ab991f2980d3 100644
--- a/test/generated_sdk/lib/collection/hash_map.dart
+++ b/test/generated_sdk/lib/collection/hash_map.dart
@@ -33,7 +33,39 @@ typedef int _Hasher<K>(K object);
  * will give matching key and value pairs.
  */
 abstract class HashMap<K, V> implements Map<K, V> {
-  @patch
+  /**
+   * Creates an unordered hash-table based [Map].
+   *
+   * The created map is not ordered in any way. When iterating the keys or
+   * values, the iteration order is unspecified except that it will stay the
+   * same as long as the map isn't changed.
+   *
+   * If [equals] is provided, it is used to compare the keys in the table with
+   * new keys. If [equals] is omitted, the key's own [Object.operator==] is used
+   * instead.
+   *
+   * Similar, if [hashCode] is provided, it is used to produce a hash value
+   * for keys in order to place them in the hash table. If it is omitted, the
+   * key's own [Object.hashCode] is used.
+   *
+   * If using methods like [operator[]], [remove] and [containsKey] together
+   * with a custom equality and hashcode, an extra `isValidKey` function
+   * can be supplied. This function is called before calling [equals] or
+   * [hashCode] with an argument that may not be a [K] instance, and if the
+   * call returns false, the key is assumed to not be in the set.
+   * The [isValidKey] function defaults to just testing if the object is a
+   * [K] instance.
+   *
+   * The used `equals` and `hashCode` method should always be consistent,
+   * so that if `equals(a, b)` then `hashCode(a) == hashCode(b)`. The hash
+   * 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) }) {
@@ -63,7 +95,13 @@ abstract class HashMap<K, V> implements Map<K, V> {
     return new _CustomHashMap<K, V>(equals, hashCode, isValidKey);
   }
 
-  @patch
+  /**
+   * Creates an unordered identity-based map.
+   *
+   * Effectively a shorthand for:
+   *
+   *     new HashMap(equals: identical, hashCode: identityHashCodeOf)
+   */
   factory HashMap.identity() = _IdentityHashMap<K, V>;
 
   /**