Backwards compat for TaskFragment + overlap fix

Add backwards compatibility for traces that didn't use the TaskFragment
on winscope. Moreover, fix the overlap calculation (using wrong object
type)

Bug: 185516271
Test: yarn run dev and open older SF and WM traces
Change-Id: I8d6c98a53cf4c5062dd7a366ef467755907dc0ed
(cherry picked from commit 752cec2b96716eb7c53b6326b0adcd8dbce98bf4)
2 files changed