[ChromeDriver] Fix typo in previous CL for util functions in

run_all_tests

Change isLinux, isMac, isWindows to IsLinux, IsMac, IsWindows

Bug: 
Change-Id: I28bcb3e753a5aaa0432350d6204b51b84d161fdd
Reviewed-on: https://chromium-review.googlesource.com/809404Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Jonathon Kereliuk <kereliuk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521749}

chrome/test/chromedriver/test/run_all_tests.py

@@ -201,19 +201,19 @@ def main():
       os.environ['CHROME_DEVEL_SANDBOX'] = '/opt/chromium/chrome_sandbox'
 
     # Linux64 build numbers
-    elif util.isLinux():
+    elif util.IsLinux():
           versions['63'] = '508578'
           versions['62'] = '499100'
           versions['61'] = '488595'
 
     # Mac build numbers
-    elif util.isMac():
+    elif util.IsMac():
           versions['63'] = '508578'
           versions['62'] = '499098'
           versions['61'] = '488595'
 
     # Windows build numbers
-    elif util.isWindows():
+    elif util.IsWindows():
           versions['63'] = '508578'
           versions['62'] = '499101'
           versions['61'] = '488595'