Revert: drop the two zero-impact commits

Per a measurement pass, two commits had zero (or negative) effect on the hello-world prod bundle:

- a0b1f09 (Move Meta mixin methods to standalone fns): bundle went from 134.17 KB → 134.19 KB (+0.02 KB). Mixin.create chain was already being tree-shaken in prod regardless.
- 75761b8 (Decouple VM debug symbols/names from opcodes.ts): bundle held at 134.12 KB. LOCAL_DEBUG=false in dist/prod (and dist/dev) was already constant-folding the debug branches out, and vite was already tree-shaking the unused @glimmer/debug imports out of the smoke-test bundle.

Both refactors were architecturally cleaner but pure no-ops at the bundle measurement that motivated this PR.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

Author: NullVoxPopuli

packages/@ember/-internals/meta/lib/meta.ts

@@ -267,6 +267,45 @@ export class Meta {
     return undefined;
   }
 
+  /** @internal */
+  addMixin(mixin: any) {
+    assert(
+      isDestroyed(this.source)
+        ? `Cannot add mixins of \`${toString(mixin)}\` on \`${toString(
+            this.source
+          )}\` call addMixin after it has been destroyed.`
+        : '',
+      !isDestroyed(this.source)
+    );
+    let set = this._getOrCreateOwnSet('_mixins');
+    set.add(mixin);
+  }
+
+  /** @internal */
+  hasMixin(mixin: any) {
+    return this._hasInInheritedSet('_mixins', mixin);
+  }
+
+  /** @internal */
+  forEachMixins(fn: Function) {
+    let pointer: Meta | null = this;
+    let seen: Set<any> | undefined;
+    while (pointer !== null) {
+      let set = pointer._mixins;
+      if (set !== undefined) {
+        seen = seen === undefined ? new Set() : seen;
+        // TODO cleanup typing here
+        set.forEach((mixin: any) => {
+          if (!seen!.has(mixin)) {
+            seen!.add(mixin);
+            fn(mixin);
+          }
+        });
+      }
+      pointer = pointer.parent;
+    }
+  }
+
   /** @internal */
   writeDescriptors(subkey: string, value: any) {
     assert(

packages/@ember/object/mixin.ts

@@ -4,53 +4,6 @@
 import { INIT_FACTORY } from '@ember/-internals/container/lib/container';
 import type { Meta } from '@ember/-internals/meta/lib/meta';
 import { meta as metaFor, peekMeta } from '@ember/-internals/meta/lib/meta';
-import { isDestroyed } from '@glimmer/destroyable';
-import toString from '@ember/-internals/utils/lib/to-string';
-
-function metaAddMixin(meta: Meta, mixin: any): void {
-  assert(
-    isDestroyed(meta.source as object)
-      ? `Cannot add mixins of \`${toString(mixin)}\` on \`${toString(
-          meta.source
-        )}\` call addMixin after it has been destroyed.`
-      : '',
-    !isDestroyed(meta.source as object)
-  );
-  let set = meta._mixins ?? (meta._mixins = new Set());
-  set.add(mixin);
-}
-
-function metaHasMixin(meta: Meta, mixin: any): boolean {
-  let pointer: Meta | null = meta;
-  while (pointer !== null) {
-    let set = pointer._mixins;
-    if (set !== undefined && set.has(mixin)) {
-      return true;
-    }
-    pointer = pointer.parent;
-  }
-  return false;
-}
-
-function metaForEachMixins(meta: Meta, fn: (mixin: any) => void): void {
-  let pointer: Meta | null = meta;
-
-  let seen: Set<any> | undefined;
-  while (pointer !== null) {
-    let set = pointer._mixins;
-    if (set !== undefined) {
-      seen = seen === undefined ? new Set() : seen;
-
-      set.forEach((mixin: any) => {
-        if (!seen!.has(mixin)) {
-          seen!.add(mixin);
-          fn(mixin);
-        }
-      });
-    }
-    pointer = pointer.parent;
-  }
-}
 import { observerListenerMetaFor, ROOT, wrap } from '@ember/-internals/utils/lib/super';
 import { assert } from '@ember/debug';
 import { DEBUG } from '@glimmer/env';
@@ -294,10 +247,10 @@ function mergeMixins(
     );
 
     if (MIXINS.has(currentMixin)) {
-      if (metaHasMixin(meta, currentMixin)) {
+      if (meta.hasMixin(currentMixin)) {
         continue;
       }
-      metaAddMixin(meta, currentMixin);
+      meta.addMixin(currentMixin);
 
       let { properties, mixins } = currentMixin;
 
@@ -639,7 +592,7 @@ export default class Mixin {
       return ret;
     }
 
-    metaForEachMixins(meta, (currentMixin: Mixin) => {
+    meta.forEachMixins((currentMixin: Mixin) => {
       // skip primitive mixins since these are always anonymous
       if (!currentMixin.properties) {
         ret.push(currentMixin);
@@ -711,7 +664,7 @@ export default class Mixin {
     if (meta === null) {
       return false;
     }
-    return metaHasMixin(meta, this);
+    return meta.hasMixin(this);
   }
 
   /** @internal */