Put timing values of DocumentTiming in a GCed object
So they can outlive the document, and PerformanceNavigationTiming can
collect them.
Bug: 40793421
Change-Id: I2cbb53862ff9fab08f963d9408ef65ff462e5dd7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5935276
Reviewed-by: David Baron dbaron@chromium.org
Commit-Queue: Guohui Deng guohuideng@microsoft.com
Reviewed-by: Noam Rosenthal nrosenthal@chromium.org
Cr-Commit-Position: refs/heads/main@{#1384608}