Move to localhost-based URL for Pica benchmark

tools/perf/page_sets/pica.json

 {
   "description": "Pica demo app for the Polymer UI toolkit",
   "archive_data_file": "../data/pica.json",
   "pages": [
-    { "url": "http://www.polymer-project.org/polymer-all/projects/pica/index.html",
+    { "url": "http://localhost/polymer/projects/pica/",
       "script_to_evaluate_on_commit":
           "document.addEventListener('WebComponentsReady', function(){var unused = document.body.offsetHeight; window.__pica_load_time = performance.now(); setTimeout(function(){window.__web_components_ready=true}, 1000)})",
       "navigate_steps" : [
         { "action": "navigate" },
         { "action": "wait", "javascript": "window.__web_components_ready" }
       ],
       "smoothness": {
         "action": "tap_element",
         "find_element_expression": "document.querySelector('pi-app').$.Topics.$.topics.$.container.querySelector('.item > .card')",
         "wait_for_event": "g-panels-select"
       }
     }
   ]
 }