lib: refactor debuglog init

lib/internal/util/debuglog.js

@@ -1,36 +1,36 @@
 'use strict';
 
 const {
-  FunctionPrototypeBind,
   ObjectCreate,
   ObjectDefineProperty,
   RegExp,
-  RegExpPrototypeTest,
+  RegExpPrototypeExec,
   SafeArrayIterator,
   StringPrototypeToLowerCase,
   StringPrototypeToUpperCase,
 } = primordials;
 
 const { inspect, format, formatWithOptions } = require('internal/util/inspect');
 
-// `debugs` is deliberately initialized to undefined so any call to
-// debuglog() before initializeDebugEnv() is called will throw.
+// `debugImpls` and `testEnabled` are deliberately not initialized so any call
+// to `debuglog()` before `initializeDebugEnv()` is called will throw.
 let debugImpls;
-
-let debugEnvRegex = /^$/;
 let testEnabled;
 
+
 // `debugEnv` is initial value of process.env.NODE_DEBUG
 function initializeDebugEnv(debugEnv) {
   debugImpls = ObjectCreate(null);
   if (debugEnv) {
+    // This is run before any user code, it's OK not to use primordials.
     debugEnv = debugEnv.replace(/[|\\{}()[\]^$+?.]/g, '\\$&')
-      .replace(/\*/g, '.*')
-      .replace(/,/g, '$|^')
-      .toUpperCase();
-    debugEnvRegex = new RegExp(`^${debugEnv}$`, 'i');
+      .replaceAll('*', '.*')
+      .replaceAll(',', '$|^');
+    const debugEnvRegex = new RegExp(`^${debugEnv}$`, 'i');
+    testEnabled = (str) => RegExpPrototypeExec(debugEnvRegex, str) !== null;
+  } else {
+    testEnabled = () => false;
   }
-  testEnabled = FunctionPrototypeBind(RegExpPrototypeTest, null, debugEnvRegex);
 }
 
 // Emits warning when user sets