EventFiringWebElement support for ElementFinder

Fixes #1538

Author: rasjani

atest/acceptance/2-event_firing_webdriver/event_firing_webdriver.robot

@@ -31,9 +31,8 @@ Event Firing Webdriver Input Text (WebElement)
     ...    LOG 1:14 INFO  After clear and send_keys
     Input Text    //input[@name="textfield"]    FooBar
 
-Event Firing Webdriver Click Element (WebElement)
+Event Firing Webdriver With Get WebElement (WebElement)
     [Tags]    NoGrid
-    [Documentation]
-    ...    LOG 1:5 INFO  Before click
-    ...    LOG 1:9 INFO  After click
-    Click Element    //input[@name="ok_button"]
+    Go To     ${ROOT}/nested_divs.html
+    ${link}=        Get WebElement    //a[@id="needleC"]
+    Wait Until Element Contains   ${link}   top/c/needle

src/SeleniumLibrary/locators/elementfinder.py

@@ -17,6 +17,7 @@
 from robot.api import logger
 from robot.utils import NormalizedDict
 from selenium.webdriver.remote.webelement import WebElement
+from selenium.webdriver.support.event_firing_webdriver import EventFiringWebElement
 
 from SeleniumLibrary.base import ContextAware
 from SeleniumLibrary.errors import ElementNotFound
@@ -102,7 +103,7 @@ def unregister(self, strategy_name):
 
     def _is_webelement(self, element):
         # Hook for unit tests
-        return isinstance(element, WebElement)
+        return isinstance(element, (WebElement, EventFiringWebElement))
 
     def _disallow_webelement_parent(self, element):
         if self._is_webelement(element):