Revert "Update all Angular libs (run update_all.sh)."

third_party/pkg/di/lib/src/key.dart

-part of di;
-
-int _lastKeyId = 0;
-int get lastKeyId => _lastKeyId;
-
-Map<int, int> _hashToKey = {};
-
-class Key {
-  final Type type;
-  final Type annotation;
-  final int hashCode;
-  final int id;
-
-  factory Key(Type type, [Type annotation]) {
-    var _hashCode = type.hashCode + annotation.hashCode;
-    var _id = _hashToKey.putIfAbsent(_hashCode, () => _lastKeyId++);
-    return new Key._newKey(type, annotation, _hashCode, _id);
-  }
-
-  Key._newKey(this.type, this.annotation, this.hashCode, this.id);
-
-  bool operator ==(other) =>
-      other is Key && other.hashCode == hashCode;
-
-  String toString() {
-    String asString = type.toString();
-    if (annotation != null) {
-      asString += ' annotated with: ${annotation.toString()}';
-    }
-    return asString;
-  }
-}