There are two issues in our current setup
1) Input events which are occurring in the same tab are going to be lost
because sync XHR. We have event handling suppression for synx XHR, so input
events are going to be discarded.
2) Input events that are happening in another tab (same process as the
synx XHR tab) are not going to be delayed. This is not correct since
sync XHR should block the Javascript execution.
This patches fixes the above cases for when both TaskController and e10s are
enabled by suspending the InputTaskManager during sync XHR, which
delays the input event handling and keeps the events around.
Differential Revision: https://phabricator.services.mozilla.com/D90780
12424aa6b0