Updating IE driver alert detection to get alert text from "repeat" alerts

This commit should allow the proper retrieval of alert text from IE alerts
that happen "repeatedly." That is, those that have the checkbox stating
"Do not let this page create any more alerts." Unlike standard Windows
alerts, these use controls that are only available via Active
Accessibility to retrieve the text. The driver now is able to detect and
retrieve text from these types of alerts.

Author: jimevans

cpp/iedriver/Alert.cpp

@@ -153,9 +153,15 @@ std::string Alert::GetText() {
   } else {
     std::string alert_text = this->GetDirectUIDialogText();
     if (!this->is_security_alert_) {
-      size_t first_crlf = alert_text.find("\r\n\r\n");
-      if (first_crlf != std::string::npos && first_crlf + 4 < alert_text.size()) {
-        alert_text_value = alert_text.substr(first_crlf + 4);
+      if (!this->is_standard_alert_) {
+        // This means the alert is from onbeforeunload, and we need to
+        // strip off everything up to and including the first CR-LF pair.
+        size_t first_crlf = alert_text.find("\r\n\r\n");
+        if (first_crlf != std::string::npos && first_crlf + 4 < alert_text.size()) {
+          alert_text_value = alert_text.substr(first_crlf + 4);
+        }
+      } else {
+        alert_text_value = alert_text;
       }
     }
   }
@@ -240,12 +246,18 @@ std::string Alert::GetDirectUIDialogText() {
     return alert_text_value;
   }
 
-  // ASSUMPTION: The second "static text" accessibility object is the one
-  // that contains the message.
+  int child_index = 0;
+  if (!this->is_standard_alert_) {
+    // ASSUMPTION: This means the alert is from onbeforeunload, and
+    // the second "static text" accessibility object is the one
+    // that contains the message.
+    child_index = 1;
+  }
+
   CComPtr<IAccessible> message_text_object = this->GetChildWithRole(
       pane_object,
       ROLE_SYSTEM_STATICTEXT,
-      1);
+      child_index);
   if (!message_text_object) {
     LOG(WARN) << "Failed to get Active Accessibility text child object from pane";
     return alert_text_value;