Revert "[ChromeDriver] Disable failing tests on Waterfall on Windows build bot"

This reverts commit 2c449f4d.

Reason for revert: Because of this was a Chromium bug and it is currently fixed, we are reverting this change.

Original change's description:
> [ChromeDriver] Disable failing tests on Waterfall on Windows build bot
> 
> Disabling failing tests testDownloadDirectoryOverridesExistingPreferences and
> testExistingDevToolsPortFile on Waterfall on Windows build bot
> 
> Bug: 907608:chromedriver:2673
> Change-Id: I74adcfa17f6349aa74805e6905fa630661ea4a9b
> Reviewed-on: https://chromium-review.googlesource.com/c/1347613
> Reviewed-by: John Chen <johnchen@chromium.org>
> Commit-Queue: Artur Khachatryan <khachatryan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#610254}

TBR=johnchen@chromium.org,khachatryan@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 907608:chromedriver:2673
Change-Id: I159363b6d2712ef07fbf0d833cce4baeea4b4fd3
Reviewed-on: https://chromium-review.googlesource.com/c/1351290Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Artur Khachatryan <khachatryan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610880}

chrome/test/chromedriver/test/run_py_tests.py

@@ -122,9 +122,6 @@ _OS_SPECIFIC_FILTER = {}
 _OS_SPECIFIC_FILTER['win'] = [
     # https://bugs.chromium.org/p/chromedriver/issues/detail?id=299
     'ChromeLogPathCapabilityTest.testChromeLogPath',
-    # https://bugs.chromium.org/p/chromedriver/issues/detail?id=2673
-    'ChromeDownloadDirTest.testDownloadDirectoryOverridesExistingPreferences',
-    'LaunchDesktopTest.testExistingDevToolsPortFile',
 ]
 _OS_SPECIFIC_FILTER['linux'] = [
 ]