Use type-safe events for TimelineTreeView
Use type-safe events for TimelineTreeView

R=04b7d4bdbd93555cee90f085bb91b72524d21fca@chromium.org

Bug: 1228674
Change-Id: I0472158bfc4c952801d9f75d7723212e462c49f8
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3161994
Reviewed-by: Kateryna Prokopenko <04b7d4bdbd93555cee90f085bb91b72524d21fca@chromium.org>
Reviewed-by: Simon Zünd <38944668e9e2ca98ccd0275b53370f90fa55c113@chromium.org>
Commit-Queue: Philip Pfaffe <639a645feae3653b7aaefa0387217d375f2f82ff@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend