Merge pull request #11604 from edx/benp/lettuce-browser

Dev user should be able to specify LETTUCE_BROWSER.

common/djangoapps/terrain/browser.py

@@ -81,8 +81,6 @@ def initial_setup(server):
             desired_capabilities['loggingPrefs'] = {
                 'browser': 'ALL',
             }
-        elif browser_driver == 'firefox':
-            desired_capabilities = DesiredCapabilities.FIREFOX
         else:
             desired_capabilities = {}
 
@@ -98,7 +96,13 @@ def initial_setup(server):
             # the browser session is invalid, this will
             # raise a WebDriverException
             try:
-                world.browser = Browser(browser_driver, desired_capabilities=desired_capabilities)
+                if browser_driver == 'firefox':
+                    # Lettuce initializes differently for firefox, and sending
+                    # desired_capabilities will not work. So initialize without
+                    # sending desired_capabilities.
+                    world.browser = Browser(browser_driver)
+                else:
+                    world.browser = Browser(browser_driver, desired_capabilities=desired_capabilities)
                 world.browser.driver.set_script_timeout(GLOBAL_SCRIPT_TIMEOUT)
                 world.visit('/')