Fix a bug in https://crrev.com/c/1272937, where event.target can be still null

Fix a bug in the previous CL, https://crrev.com/c/1272937, where event.target
can be null when GetElement() returns nullptr.

Bug: 892970, 893449, 902287
Change-Id: I7a08227d39117c2dc90fe720f0d6ffd62d9b2ea6
Reviewed-on: https://chromium-review.googlesource.com/c/1322177
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606884}
1 file changed