Revert "[compiler,api] Pass non-strings to the modifying callback when unconditional codegen is on."

This reverts commit 0c9a0072.

Reason for revert: Breaks tests on the blink bots, will block roll.
https://ci.chromium.org/p/v8/builders/ci/V8%20Blink%20Linux/4465

Original change's description:
> [compiler,api] Pass non-strings to the modifying callback when unconditional codegen is on.
> 
> In the current state, when unconditional compilation is on, strings are evaluated and other objects are passed through unchanged. After this, non-strings are passed to the modifying callback which could unwrap and eval them. eval(string) is not affected.
> 
> If a non-modifying callback is set, it still takes the precedence, and the non-string object is returned as it would be currently (line 1933).
> 
> Change-Id: I835b976b3420635baba245c08f8563a9e5b3b246
> Bug: chromium:1024786
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1917147
> Commit-Queue: Stefano Sanfilippo <ssanfilippo@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Reviewed-by: Michael Stanton <mvstanton@chromium.org>
> Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#67570}

TBR=vogelheim@chromium.org,mvstanton@chromium.org,ssanfilippo@chromium.org,verwaest@chromium.org

Change-Id: I75637347e92e805361f954be3515f84ca55d756b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1024786
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2182178Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67577}