gwt 2.6.0

Closes #26626.
boot2docker: make dependency on docker recommended

Closes #26435.
Closes #26627.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
geoipupdate: fix build on 10.6

Fixes #25865.
libzdb 3.0

Closes #26630.
dart 1.1.3 (32314)

Added public version number in addition to revision number to easily figure out the current version of dart on brew.