[ChromeDriver] Enable window maximize tests on Mac

With the updated Java tests window maximize tests are now passing.
Enabling these tests.

Change-Id: I01c701564b8f668b9d660126d373e36df24c0a34
Reviewed-on: https://chromium-review.googlesource.com/c/1457204Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Artur Khachatryan <khachatryan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629776}

chrome/test/chromedriver/test/test_expectations

@@ -47,9 +47,6 @@ _OS_NEGATIVE_FILTER['mac'] = [
     'WindowTest.canFullscreenTheWindowFromFrame',
     'WindowTest.canFullscreenTheWindowFromIframe',
     'WindowTest.testSetsTheSizeOfTheCurrentWindow',
-    'WindowTest.testCanMaximizeTheWindowFromFrame',
-    'WindowTest.testCanMaximizeTheWindowFromIframe',
-    'WindowTest.testCanMaximizeTheWindow',
     'BasicMouseInterfaceTest.testMovingMouseByRelativeOffset',
 ]