Revert "Reland "refactor(core): cleanup feature flags for js source i… (#19611)

…nclusion" (#19519)"

This reverts commit 28a4f3d0f5383695b1d49ccdc8b0f799a715b2c2.

This change causes failures when used outside Deno repo:
```
============================================================
Deno has panicked. This is a bug in Deno. Please report this
at https://github.com/denoland/deno/issues/new.
If you can reliably reproduce this panic, include the
reproduction steps and re-run with the RUST_BACKTRACE=1 env
var set and include the backtrace in your report.

Platform: linux x86_64
Version: 1.34.3+b37b286
Args: ["/opt/hostedtoolcache/deno/0.0.0-b37b286f7fa68d5656f7c180f6127bdc38cf2cf5/x64/deno", "test", "--doc", "--unstable", "--allow-all", "--coverage=./cov"]

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Failed to read "/home/runner/work/deno/deno/core/00_primordials.js"

Caused by:
    No such file or directory (os error 2)', core/runtime/jsruntime.rs:699:8
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

1 files changed, 0 insertions, 7 deletions

diff --git a/core/02_error.js b/core/02_error.js
index c082486f4..b29dc9b4e 100644
--- a/core/02_error.js
+++ b/core/02_error.js
@@ -14,15 +14,8 @@
     ArrayPrototypePush,
     ArrayPrototypeMap,
     ArrayPrototypeJoin,
-    SymbolFor,
   } = window.__bootstrap.primordials;
 
-  const key = SymbolFor("02_error.js");
-  if (globalThis.__bootstrap[key]) {
-    return;
-  }
-  globalThis.__bootstrap[key] = true;
-
   // Keep in sync with `cli/fmt_errors.rs`.
   function formatLocation(cse) {
     if (cse.isNative) {