Update chromedriver to 2.19 and iedriver to 2.47

[anufryieu]

I updated chromedriver to 2.19 and iedriver to 2.47

#2393

[googlebot]

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[anufryieu]

I signed!

[googlebot]

CLAs look good, thanks!

[juliemr]

We need to make sure that the issue documented in #2245 has been fixed up before we can do a full update. Just to note that this will take some more investigation.

[juliemr]

Done in cfd8d00 (and with changes to our CI as well). Thanks for the PR!

[anufryieu]

Thanks!