Suppress "not JSON strings" warning if `filename` argument is provided

IPython/core/display.py

@@ -655,7 +655,8 b' class JSON(DisplayObject):'
     @data.setter
     def data(self, data):
         if isinstance(data, str):
-            warnings.warn("JSON expects JSONable dict or list, not JSON strings")
+            if self.filename is None:
+                warnings.warn("JSON expects JSONable dict or list, not JSON strings")
             data = json.loads(data)
         self._data = data
 
@@ -689,6 +690,8 b' class GeoJSON(JSON):'
     @data.setter
     def data(self, data):
         if isinstance(data, str):
+            if self.filename is None:
+                warnings.warn("GeoJSON expects JSONable dict or list, not JSON strings")
             data = json.loads(data)
         self._data = data