Add robohornet as an animation test

tools/perf/page_sets/tough_texture_upload_cases.json

 {
   "description": "A collection of texture upload performance tests",
   "pages": [
     {
       "url": "file:///tough_texture_upload_cases/background_color_animation.html",
-      "scrolling": {
+      "smoothness": {
           "action": "scrolling_interaction"
       }
     },
     {
       "url": "file:///tough_texture_upload_cases/background_color_animation_and_transform_animation.html",
-      "scrolling": {
+      "smoothness": {
           "action": "scrolling_interaction"
       }
     },
     {
       "url": "file:///tough_texture_upload_cases/background_color_animation_with_gradient.html",
-      "scrolling": {
+      "smoothness": {
           "action": "scrolling_interaction"
       }
     },
     {
       "url": "file:///tough_texture_upload_cases/background_color_animation_with_gradient_and_transform_animation.html",
-      "scrolling": {
+      "smoothness": {
           "action": "scrolling_interaction"
       }
     }
   ]
 }