Enable webview for Poll & Survey blocks.

poll/poll.py

@@ -360,6 +360,7 @@ class PollBlock(PollBase):
         else:
             return None
 
+    @XBlock.supports("multi_device")  # Mark as mobile-friendly
     def student_view(self, context=None):
         """
         The primary view of the PollBlock, shown to students
@@ -582,6 +583,7 @@ class SurveyBlock(PollBase):
     choices = Dict(help="The user's answers", scope=Scope.user_state)
     event_namespace = 'xblock.survey'
 
+    @XBlock.supports("multi_device")  # Mark as mobile-friendly
     def student_view(self, context=None):
         """
         The primary view of the SurveyBlock, shown to students