fix: Fixed AttributeError when working with Blobs and Buckets

Fixes googleapis#540

google/cloud/storage/bucket.py

@@ -41,6 +41,7 @@
 from google.cloud.storage.acl import BucketACL
 from google.cloud.storage.acl import DefaultObjectACL
 from google.cloud.storage.blob import Blob
+from google.cloud.storage.client import Client
 from google.cloud.storage.constants import _DEFAULT_TIMEOUT
 from google.cloud.storage.constants import ARCHIVE_STORAGE_CLASS
 from google.cloud.storage.constants import COLDLINE_STORAGE_CLASS
@@ -610,7 +611,7 @@ def __init__(self, client, name=None, user_project=None):
         """
         name = _validate_name(name)
         super(Bucket, self).__init__(name=name)
-        self._client = client
+        self._client = client or Client()
         self._acl = BucketACL(self)
         self._default_object_acl = DefaultObjectACL(self)
         self._label_removals = set()