It was broken in https://codereview.chromium.org/2547483002.

The following revision refers to this bug:
  https://chromium.googlesource.com/v8/v8.git/+/3dea2c83541af5c0f65044c4224f15d919254a4c

commit 3dea2c83541af5c0f65044c4224f15d919254a4c
Author: kozyatinskiy <kozyatinskiy@chromium.org>
Date: Wed Dec 14 02:04:10 2016

Revert of Store SharedFunctionInfos of a Script in a FixedArray indexed by their ID (patchset #11 id:190001 of https://codereview.chromium.org/2547483002/ )

Reason for revert:
LiveEdit is broken in some cases.

Original issue's description:
> Store SharedFunctionInfos of a Script in a FixedArray indexed by their ID
>
> Now that SharedFunctionInfos have a unique ID (and the IDs are dense),
> we can use them as an index into an array, instead of using a
> WeakFixedArray where we have to do a linear scan.
>
> Hooking up liveedit is a bit more involved, see
> https://docs.google.com/presentation/d/1FtNa3U7WsF5bPhY9uGoJG5Y9hnz5VBDabfOWpb4unWI/edit
> for an overview
>
> BUG= v8:5589 
> R=verwaest@chromium.org,jgruber@chromium.org
>
> Committed: https://crrev.com/6595e7405769dc9d49e9568d61485efc6d468baf
> Cr-Commit-Position: refs/heads/master@{#41600}

TBR=jgruber@chromium.org,verwaest@chromium.org,yangguo@chromium.org,jochen@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG= v8:5589 , chromium:673950 
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2578433002
Cr-Commit-Position: refs/heads/master@{#41684}

[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/bootstrapper.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/compiler.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/crankshaft/hydrogen.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/debug/debug.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/debug/liveedit.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/debug/liveedit.h
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/debug/liveedit.js
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/factory.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/heap/heap.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/heap/object-stats.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/js/promise.js
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/objects-inl.h
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/objects.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/objects.h
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/parsing/parse-info.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/parsing/parse-info.h
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/parsing/parser.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/runtime/runtime-function.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/runtime/runtime-liveedit.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/src/runtime/runtime.h
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/test/cctest/heap/test-heap.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/test/cctest/parsing/test-parse-decision.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/test/cctest/test-serialize.cc
[modify] https://crrev.com/3dea2c83541af5c0f65044c4224f15d919254a4c/test/unittests/compiler-dispatcher/compiler-dispatcher-job-unittest.cc

hum, I wonder whether a bug without a revert would have been sufficient here? after all, this case isn't covered by tests, and the revert ripped out a large part of infrastructure...

We actively use live edit during DevTools front end development and this issue broke our process.
Will git cl format help infrastructure next time? Do I need to think about something else in infrastructure in addition to green bots?

not sure what you mean with git cl format?

if it's development, you can revert locally (and you can still add tests for features you rely on)

fix is in the CQ https://codereview.chromium.org/2577063002/

Thanks for fix!
Ok. Our frontend development process is similar with regular web development process, it means if it doesn't work for us then our users have the same problem. They can't just revert patch locally.
My question is: why infrastructure was ripped out by revert? What is right way to revert something in V8?