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

tools/perf/page_sets/key_desktop_sites.json

 {
   "description": "Sites of Interest",
   "archive_data_file": "../data/sites_of_interest.json",
   "credentials_path": "../data/credentials.json",
   "smoothness": { "action": "scroll" },
   "pages": [
     {
       "url": "http://facebook.com",
       "credentials": "facebook"
     },
@@ skipping 602 matching lines @@
     { "url": "http://rei.com" },
     { "url": "http://liverpoolfc.tv" },
     { "url": "http://deadspin.com" },
     { "url": "http://sbnation.com" },
     { "url": "https://www.google.com" },
     { "url": "https://www.google.com/search?q=barack%20obama" },
     {
       "url": "https://mail.google.com/mail/",
       "credentials": "google",
       "scrollable_element_function": "function(callback) { gmonkey.load('2.0', function(api) { callback(api.getScrollableElement()); }); }",
-      "smoothness": {
-        "action": "scroll",
-        "wait_for_javascript_expression": "window.gmonkey !== undefined && document.getElementById('gb') !== null"
-      }
+      "smoothness": [
+        { "action": "scroll" },
+        { "action": "wait", "javascript": "window.gmonkey !== undefined && document.getElementById('gb') !== null" }
+      ]
     },
     {
       "url": "https://www.google.com/calendar/",
       "credentials": "google",
       "scrollable_element_function": "function(callback) { callback(document.getElementById('scrolltimedeventswk')); }"
     },
     {
       "url": "https://drive.google.com",
       "credentials": "google",
       "scrollable_element_function": "function(callback) { callback(document.getElementsByClassName('doclistview-list')[0]); }",
-      "smoothness": {
-        "action": "scroll",
-        "wait_for_javascript_expression": "document.getElementsByClassName('doclistview-list').length"
-      }
+      "smoothness": [
+        { "action": "scroll" },
+        { "action": "wait", "javascript": "document.getElementsByClassName('doclistview-list').length" }
+      ]
     },
     {
       "url": "https://docs.google.com/a/google.com/document/d/1XMAtPiVFZfItsMUOYl39v5YA8bcSPe4LDrVO25OdsCU/edit",
       "credentials": "google",
       "scrollable_element_function": "function(callback) { callback(document.getElementsByClassName('kix-appview-editor')[0]); }",
-      "smoothness": {
-        "action": "scroll",
-        "wait_for_javascript_expression": "document.getElementsByClassName('kix-appview-editor').length"
-      }
+      "smoothness": [
+        { "action": "scroll" },
+        { "action": "wait", "javascript": "document.getElementsByClassName('kix-appview-editor').length" }
+      ]
     },
     { "url": "https://maps.google.com" },
     { "url": "http://reader.google.com" },
     { "url": "https://plus.google.com/110031535020051778989/posts/2wP4KPPBMG8" },
     { "url": "https://plus.google.com/110031535020051778989/photos" },
     { "url": "http://googleblog.blogspot.com/" },
     { "url": "https://chrome.google.com/webstore/category/home" },
     { "url": "http://staff.tumblr.com/" },
     { "url": "http://mashable.com/" },
     { "url": "http://www.buzzfeed.com/celebrity" },
@@ skipping 80 matching lines @@
     { "url": "http://maps.google.com" },
     { "url": "https://www.google.com/search?num=10&hl=en&site=&tbm=isch&q=cats" },
     { "url": "http://code.google.com/p/chromium/issues/list" },
     { "url": "http://code.google.com/p/chromium/issues/detail?id=142038&q=black%20screen%20amd&colspec=ID%20Pri%20Mstone%20ReleaseBlock%20OS%20Area%20Feature%20Status%20Owner%20Summary" },
     { "url": "http://mlb.mlb.com/index.jsp" },
     { "url": "http://www.nfl.com/" },
     { "url": "http://airbnb.github.com/infinity/demo-on.html" },
     { "url": "http://habrahabr.ru/post/149892/#habracut" }
   ]
 }