Add null test and remove redundant call.

- Did not handle the case where mTaskIdToTask returned null.
Fixes bug 8646178.
- updateInputWindowsLw() was being called in removeWindows
immediately after it was called in performLayoutAndUpdateSurfaces.

Change-Id: I1b8bcfadcc93f8c6638fd4247b426af77feeee23
2 files changed