[py] Use Color in rendered_webelement_tests (#5360)

WebDriver spec decided that CSS values returned should be whatever the
browser returns, without imposing any format for colors. By using Color
class in the tests we can compare colors even if different formats (RGB
vs RGBA) are used.

py/test/selenium/webdriver/common/rendered_webelement_tests.py

@@ -19,27 +19,26 @@
 
 from selenium.common.exceptions import WebDriverException
 from selenium.webdriver.common.by import By
+from selenium.webdriver.support.color import Color
 
 
-@pytest.mark.xfail_marionette(
-    reason='https://github.com/w3c/webdriver/issues/417')
 def testShouldPickUpStyleOfAnElement(driver, pages):
     pages.load("javascriptPage.html")
 
     element = driver.find_element(by=By.ID, value="green-parent")
-    backgroundColour = element.value_of_css_property("background-color")
-    assert "rgba(0, 128, 0, 1)" == backgroundColour
+    backgroundColour = Color.from_string(element.value_of_css_property("background-color"))
+    assert Color.from_string("rgba(0, 128, 0, 1)") == backgroundColour
 
     element = driver.find_element(by=By.ID, value="red-item")
-    backgroundColour = element.value_of_css_property("background-color")
-    assert "rgba(255, 0, 0, 1)" == backgroundColour
+    backgroundColour = Color.from_string(element.value_of_css_property("background-color"))
+    assert Color.from_string("rgba(255, 0, 0, 1)") == backgroundColour
 
 
 def testShouldAllowInheritedStylesToBeUsed(driver, pages):
     pages.load("javascriptPage.html")
     element = driver.find_element(by=By.ID, value="green-item")
-    backgroundColour = element.value_of_css_property("background-color")
-    assert backgroundColour in ("rgba(0, 0, 0, 0)", "transparent")
+    backgroundColour = Color.from_string(element.value_of_css_property("background-color"))
+    assert backgroundColour == Color.from_string("transparent")
 
 
 def testShouldCorrectlyIdentifyThatAnElementHasWidth(driver, pages):