Description of problem:
----------------------
The UI blows up with this error while drilling into Availability zone C&U graphs.

Error text:
undefined method `[]' for nil:NilClass [availability_zone/show] 

Snippet from production.log:

[----] I, [2016-10-12T13:24:58.817897 #11810:1686edc]  INFO -- : Started POST "/availability_zone/show/13?menu_click=Display-VMs-on_-1-15-0" for 127.0.0.1 at 2016-10-12 13:24:58 -0400
[----] I, [2016-10-12T13:24:58.820625 #11810:1686edc]  INFO -- : Processing by AvailabilityZoneController#show as JS
[----] I, [2016-10-12T13:24:58.820734 #11810:1686edc]  INFO -- :   Parameters: {"menu_click"=>"Display-VMs-on_-1-15-0", "id"=>"13"}
[----] F, [2016-10-12T13:24:58.854205 #11810:1686edc] FATAL -- : Error caught: [NoMethodError] undefined method `[]' for nil:NilClass
/var/www/miq/vmdb/app/controllers/application_controller/performance.rb:258:in `perf_menu_click'
/var/www/miq/vmdb/app/helpers/application_helper.rb:1042:in `perfmenu_click?'
/var/www/miq/vmdb/app/controllers/availability_zone_controller.rb:12:in `show'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/basic_implicit_render.rb:4:in `send_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/abstract_controller/base.rb:188:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/rendering.rb:30:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/abstract_controller/callbacks.rb:20:in `block in process_action'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:126:in `call'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:506:in `block (2 levels) in compile'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:455:in `call'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:101:in `__run_callbacks__'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:750:in `_run_process_action_callbacks'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:90:in `run_callbacks'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/abstract_controller/callbacks.rb:19:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/rescue.rb:20:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/notifications.rb:164:in `block in instrument'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/notifications.rb:164:in `instrument'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/instrumentation.rb:30:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/params_wrapper.rb:248:in `process_action'
/opt/rh/cfme-gemset/gems/activerecord-5.0.0.1/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/abstract_controller/base.rb:126:in `process'
/opt/rh/cfme-gemset/gems/actionview-5.0.0.1/lib/action_view/rendering.rb:30:in `process'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal.rb:190:in `dispatch'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal.rb:262:in `dispatch'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_dispatch/routing/route_set.rb:50:in `dispatch'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_dispatch/routing/route_set.rb:32:in `serve'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_dispatch/journey/router.rb:39:in `block in serve'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_dispatch/journey/router.rb:26:in `each'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_dispatch/journey/router.rb:26:in `serve'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_dispatch/routing/route_set.rb:725:in `call'
/opt/rh/cfme-gemset/gems/secure_headers-3.0.3/lib/secure_headers/middleware.rb:10:in `call'
/opt/rh/cfme-gemset/gems/rack-2.0.1/lib/rack/etag.rb:25:in `call'
/opt/rh/cfme-gemset/gems/rack-2.0.1/lib/rack/conditional_get.rb:38:in `call'
/opt/rh/cfme-gemset/gems/rack-2.0.1/lib/rack/head.rb:12:in `call'
/opt/rh/cfme-gemset/gems/rack-2.0.1/lib/rack/session/abstract/id.rb:222:in `context'
/opt/rh/cfme-gemset/gems/rack-2.0.1/lib/rack/session/abstract/id.rb:216:in `call'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/cookies.rb:613:in `call'



Version-Release number of selected component (if applicable):
------------------------------
5.7.0.4


How reproducible:
----------------
Always


Steps to Reproduce:
-------------------
1.Manage a cloud provider.Enable C&U collection for the provider.
2.From the summary page of any Availability zone, click 'Monitoring', then click 'Utilization'.
3.Drill into the C&U graphs by left clicking any of the data points.
Eg: Click Chart, click 'Top instances during this hour' or 'Back to Daily'.



Actual results:
---------------
UI blows up.


Expected results:
----------------
No UI errors


Additional info:
----------------