Removing Page.WaitToLoad and update all pagesets to use explicit wait actions

tools/perf/page_sets/2012Q3.json

 {
   "description": "Pages hand-picked from top-lists in Q32012.",
   "archive_data_file": "../data/2012Q3.json",
   "credentials_path": "../data/credentials.json",
   "smoothness": { "action": "scroll" },
-  "reload_and_gc": [{"action": "reload", "wait_seconds": 1}, {"action": "js_collect_garbage"}],
+  "reload_and_gc": [
+    {"action": "reload" },
+    {"action": "wait", "seconds": 1 },
+    {"action": "js_collect_garbage" }
+  ],
   "stress_memory": { "action": "reload_and_gc", "repeat": 3 },
   "pages": [
     { "url": "http://www.facebook.com/barackobama" },
     { "url": "https://www.google.com/search?q=barack%20obama" },
     { "url": "http://youtube.com" },
     { "url": "http://yahoo.com" },
     { "url": "http://www.baidu.com/s?wd=barack+obama" },
     { "url": "http://en.wikipedia.org/wiki/Wikipedia" },
     { "url": "http://qq.com" },
     { "url": "http://www.amazon.com/Kindle-Fire-Amazon-Tablet/dp/B0051VVOB2" },
@@ skipping 202 matching lines @@
     { "url": "http://php.net" },
     { "url": "http://www.target.com/c/women/-/N-5xtd3#?lnk=nav_t_spc_1_0" },
     { "url": "http://dianxin.cn" },
     { "url": "http://www.aizhan.com/siteall/www.youboy.com/" },
     { "url": "http://veiculos-home.mercadolivre.com.br/" },
     { "url": "http://kakaku.com" },
     { "url": "http://flipkart.com" },
     { "url": "http://paipai.com" }
   ]
 }