hg: openjfx/8u-dev/rt: 8210218: WebKit build fails with newer versions of VS 2017

[arunprasad.rajkumar at oracle.com]

Changeset: 2a3a923983ef
Author:    arajkumar
Date:      2018-09-21 10:24 +0530
URL:       http://hg.openjdk.java.net/openjfx/8u-dev/rt/rev/2a3a923983ef

8210218: WebKit build fails with newer versions of VS 2017
Reviewed-by: kcr, jvos

! modules/web/src/main/native/Source/WTF/wtf/Variant.h