Instead of attaching an event handler to every line in the code view,
attach it only to the container and find the lineNumber based on the event
target element.

Notry: true
Change-Id: I1920f7a200cf2f5ffaf259c0aaa04d6fb6698d2d
Bug: v8:7327
Reviewed-on: https://chromium-review.googlesource.com/c/1346110
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57670}