This reverts commit 2608ecc7.

Revert "Specialize helper methods in the LookupIterator by is_element."

This reverts commit 6eb483f8.

Revert "Avoid SetPropertyInternal if the LookupIterator is NotFound"

This reverts commit ca5bd8d4.

Revert "Inline fast-bailout-checks for LookupIterator::UpdateProtector"

This reverts commit d98570a1.

This breaks layout tests with timeouts:
https://build.chromium.org/p/client.v8.fyi/builders/V8-Blink%20Linux%2064/builds/5060

It also seems to break jsfunfuzz:
https://build.chromium.org/p/client.v8/builders/V8%20Fuzzer/builds/7930

The other three CLs are reverted to be able to revert the first.

BUG=v8:4798
LOG=n
TBR=verwaest@chromium.org

Review URL: https://codereview.chromium.org/1761593003

Cr-Commit-Position: refs/heads/master@{#34457}