infra: run flake8 in webdriver/

Bug: web-platform-tests/rfcs#171

Author: Thiago Perrotta

tools/flake8.ini

@@ -10,14 +10,15 @@ select = E,W,F,N
 # E303: too many blank lines (3)
 # E305: expected 2 blank lines after end of function or class
 # E402: module level import not at top of file
+# E501: line too long
 # E731: do not assign a lambda expression, use a def
 # W504: line break after binary operator
 # W601: .has_key() is deprecated, use ‘in’
 # N801: class names should use CapWords convention
 # N802: function name should be lowercase
 # N806: variable in function should be lowercase
 # N818: exception should be named with an Error suffix
-ignore = E128,E129,E226,E231,E251,E265,E302,E303,E305,E402,E731,W504,W601,N801,N802,N806,N818
+ignore = E128,E129,E226,E231,E251,E265,E302,E303,E305,E402,E501,E731,W504,W601,N801,N802,N806,N818
 exclude =
     .tox,
     third_party,

tools/tox.ini

@@ -15,7 +15,7 @@ changedir =
 
 commands =
   !flake8-!mypy: pytest --cov=tools --cov-report=term {posargs}
-  flake8: flake8 --append-config={toxinidir}/flake8.ini {posargs}
+  flake8: flake8 --append-config={toxinidir}/flake8.ini {toxinidir} {toxinidir}/../webdriver {posargs}
   mypy: mypy --config-file={toxinidir}/mypy.ini --explicit-package-bases tools
 
 passenv =