Setup basic Runtime with properties and platform.

recipe_engine/loader.py

Index: recipe_engine/loader.py
diff --git a/recipe_engine/loader.py b/recipe_engine/loader.py
index 97927de48d84daed0a6ba66ebe65ad3273c05a79..9c0ac31916dbf3d2129d384887158a505ac4c53d 100644
--- a/recipe_engine/loader.py
+++ b/recipe_engine/loader.py
@@ -68,13 +68,13 @@ class RecipeScript(object):
   def RETURN_SCHEMA(self):
     return self._recipe_globals.get('RETURN_SCHEMA')
 
-  def run(self, api, properties):
+  def run(self, api, rt):
     """
     Run this recipe, with the given api and property arguments.
     Check the return value, if we have a RETURN_SCHEMA.
     """
     recipe_result = invoke_with_properties(
-      self.run_steps, properties, self.PROPERTIES, api=api)
+      self.run_steps, rt.mutable_properties(), self.PROPERTIES, api=api)
 
     if self.RETURN_SCHEMA:
       if not recipe_result: