An obvious bug crept in setVisible where setVisible(true) twice would
end up hiding the window.

BUG=angleproject:1145

Change-Id: Iea8ca3de4ab8c05e6da66fb04c8d377824547b41
Reviewed-on: https://chromium-review.googlesource.com/324090
Tryjob-Request: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>