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

tools/perf/page_sets/top_10.json

 {
   "description": "10 Pages chosen from Alexa top sites.",
   "archive_data_file": "../data/top_10.json",
   "credentials_path": "../data/credentials.json",
   "user_agent_type": "desktop",
   "smoothness": { "action": "scroll" },
   "pages": [
     {
       "url": "https://www.google.com/#hl=en&q=barack+obama",
       "why": "top google property; a google tab is often open",
-      "wait_for_element_with_text": "Next"
+      "navigate_steps" : [
+        { "action": "navigate" },
+        { "action": "wait", "condition": "element", "text": "Next" }
+      ]
     },
     {
       "url": "https://mail.google.com/mail/",
       "why": "productivity, top google properties",
       "credentials": "google",
-      "wait_for_javascript_expression": "window.gmonkey !== undefined && document.getElementById('gb') !== null"
+      "navigate_steps" : [
+        { "action": "navigate" },
+        { "action": "wait", "javascript": "window.gmonkey !== undefined && document.getElementById('gb') !== null" }
+      ]
     },
     {
       "url": "https://www.google.com/calendar/",
       "why": "productivity, top google properties",
       "credentials": "google",
-      "wait_for_element_with_selector": "div[class~=\"navForward\"]",
-      "post_navigate_javascript_to_execute": "(function() { var elem = document.createElement('meta');elem.name='viewport';elem.content='initial-scale=1';document.body.appendChild(elem); })();",
-      "wait_seconds": 2
+      "navigate_steps" : [
+        { "action": "navigate" },
+        { "action": "javascript", "expression": "(function() { var elem = document.createElement('meta');elem.name='viewport';elem.content='initial-scale=1';document.body.appendChild(elem); })();" },
+        { "action": "wait", "seconds": 2 },
+        { "action": "wait", "condition": "element", "selector": "div[class~=\"navForward\"]" }
+      ]
     },
     {
       "url": "http://www.youtube.com",
       "why": "#3 (Alexa global)",
-      "wait_seconds": 2,
+      "navigate_steps" : [
+        { "action": "navigate" },
+        { "action": "wait", "seconds": 2 }
+      ],
       "credentials": "google"
     },
     {
       "name": "Facebook",
       "url": "http://www.facebook.com/barackobama",
       "why": "top social,Public profile",
       "credentials": "facebook",
-      "wait_for_element_with_text": "About"
+      "navigate_steps" : [
+        { "action": "navigate" },
+        { "action": "wait", "condition": "element", "text": "About" }
+      ]
     },
     {
       "name": "Wikipedia (1 tab)",
       "url": "http://en.wikipedia.org/wiki/Wikipedia",
       "why": "#6 (Alexa) most visited worldwide,Picked an interesting page"
     },
     {
       "url": "http://www.amazon.com",
       "why": "#1 world commerce website by visits; #3 commerce in the US by time spent"
     },
     {
       "url": "http://www.yahoo.com/",
       "why": "#4 Alexa"
     },
     {
       "url": "http://www.bing.com/",
       "why": "#16 Alexa"
     },
     {
       "url": "http://www.ask.com/",
       "why": "#20 Alexa"
     }
   ]
 }