Add Wait* API to ActionRunner to wrap over WaitAction.

tools/telemetry/telemetry/page/actions/wait.py

Index: tools/telemetry/telemetry/page/actions/wait.py
diff --git a/tools/telemetry/telemetry/page/actions/wait.py b/tools/telemetry/telemetry/page/actions/wait.py
index 6ff37d803577a2b0a0358a02095049d33f50f25e..9de6b484f7f56f0a786416354c0d47d80b7e6e93 100644
--- a/tools/telemetry/telemetry/page/actions/wait.py
+++ b/tools/telemetry/telemetry/page/actions/wait.py
@@ -42,6 +42,9 @@ class WaitAction(page_action.PageAction):
                                    'null)'
                   '.singleNodeValue' % re.escape(self.xpath))
         tab.WaitForJavaScriptExpression('%s != null' % code, self.timeout)
+      elif hasattr(self, 'element_function'):
+        tab.WaitForJavaScriptExpression(
+            '%s != null' % self.element_function, self.timeout)
       else:
         raise page_action.PageActionFailed(
             'No element condition given to wait')