Small improvement to PropertiesClient.

This no longer requires a reference to the RecipeEngine.

R=tandrii@chromium.org

Bug: 910369
Change-Id: Ief9403c379339e8697cdcd60457d5644e5a77d4e
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/recipes-py/+/1601457
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>
Auto-Submit: Robbie Iannucci <iannucci@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
diff --git a/recipe_engine/internal/engine.py b/recipe_engine/internal/engine.py
index 543bd88..35f32f1 100644
--- a/recipe_engine/internal/engine.py
+++ b/recipe_engine/internal/engine.py
@@ -116,7 +116,7 @@
     self._environ = environ.copy()
     self._clients = {client.IDENT: client for client in (
         recipe_api.PathsClient(),
-        recipe_api.PropertiesClient(self),
+        recipe_api.PropertiesClient(properties),
         recipe_api.SourceManifestClient(self, properties),
         recipe_api.StepClient(self),
     )}
diff --git a/recipe_engine/recipe_api.py b/recipe_engine/recipe_api.py
index d4b778b..8af1919 100644
--- a/recipe_engine/recipe_api.py
+++ b/recipe_engine/recipe_api.py
@@ -172,11 +172,11 @@
 
   IDENT = 'properties'
 
-  def __init__(self, engine):
-    self._engine = engine
+  def __init__(self, properties):
+    self._properties = properties
 
   def get_properties(self):
-    return copy.deepcopy(self._engine.properties)
+    return copy.deepcopy(self._properties)
 
 
 class StepClient(object):