Fix native scrolling regression in iOS 6 homescreen apps (#12295)

Change-Id: Ie225663ebc2a9ffe4b481a49e34e9dcf79b064b2
Fix race in VaadinService.lockSession() (#12282)

The session might be invalidated before lockSession() acquires the lock.
Check if the session is still valid after locking and ensure
SessionExpiredException is thrown if not.

Change-Id: Iad716332a65b7c198427fce5198f6808140c140c
Update "lastRequestedFirstvisible" field value right away (#10666).

Change-Id: Idef31fa74f4720b5c55511de0545cd8ae1b77b26
Disable failing calendar Actions Menu Test (#12181)

This test cannot be completed in a smart fashion until TestBench 3 is in
use, because of differences in the DOM structure created by GWT for IE
and Opera, versus Webkit and Gecko browsers. TB2 requires identical DOM
structure for assertion queries to work.

Change-Id: I6f5f9aac1c25e4e105459da215db080b031b2aab
Split UiAccess test (#12332)

Change-Id: I231e84d84adca79549d00a88dd4ae613ff291dbc
Merge changes from origin/7.1

16d17f9 Fix native scrolling regression in iOS 6 homescreen apps (#12295)
7212e02 Fix race in VaadinService.lockSession() (#12282)
2d5a107 Update "lastRequestedFirstvisible" field value right away (#10666).
325cdf9 Disable failing calendar Actions Menu Test (#12181)
8ba4117 Split UiAccess test (#12332)

Change-Id: I30e7aaacaf0ecbdc1a6dbdf956a6e48f4846de32