Revert "fix(material/form-field): outline label position (#29138)" (#29282)

This reverts commit 6318f24.

(cherry picked from commit 5b52082)

Author: crisbeto

src/material/form-field/form-field.ts

@@ -7,8 +7,8 @@
  */
 import {Directionality} from '@angular/cdk/bidi';
 import {BooleanInput, coerceBooleanProperty} from '@angular/cdk/coercion';
+import {Platform} from '@angular/cdk/platform';
 import {DOCUMENT, NgTemplateOutlet} from '@angular/common';
-import {Platform, _getShadowRoot} from '@angular/cdk/platform';
 import {
   ANIMATION_MODULE_TYPE,
   AfterContentChecked,
@@ -315,13 +315,6 @@ export class MatFormField
   private _explicitFormFieldControl: MatFormFieldControl<any>;
   private _needsOutlineLabelOffsetUpdate = false;
 
-  /**
-   * Cached shadow root that the element is placed in. `null` means that the element isn't in
-   * the shadow DOM and `undefined` means that it hasn't been resolved yet. Should be read via
-   * `_getShadowRoot`, not directly.
-   */
-  private _cachedShadowRoot: ShadowRoot | null | undefined;
-
   private _injector = inject(Injector);
 
   constructor(
@@ -718,29 +711,14 @@ export class MatFormField
   /** Checks whether the form field is attached to the DOM. */
   private _isAttachedToDom(): boolean {
     const element: HTMLElement = this._elementRef.nativeElement;
-    const rootNode = element.getRootNode();
-    // If the element is inside the DOM the root node will be either the document,
-    // the closest shadow root or an element that is not yet rendered, otherwise it'll be the element itself.
-    return (
-      rootNode &&
-      rootNode !== element &&
-      // If the rootNode is the document we need to make sure that the element is visible
-      ((rootNode === document && element.offsetParent !== null) ||
-        rootNode === this._getShadowRoot())
-    );
-  }
-
-  /**
-   * Lazily resolves and returns the shadow root of the element. We do this in a function, rather
-   * than saving it in property directly on init, because we want to resolve it as late as possible
-   * in order to ensure that the element has been moved into the shadow DOM. Doing it inside the
-   * constructor might be too early if the element is inside of something like `ngFor` or `ngIf`.
-   */
-  private _getShadowRoot(): ShadowRoot | null {
-    if (this._cachedShadowRoot === undefined) {
-      this._cachedShadowRoot = _getShadowRoot(this._elementRef.nativeElement);
+    if (element.getRootNode) {
+      const rootNode = element.getRootNode();
+      // If the element is inside the DOM the root node will be either the document
+      // or the closest shadow root, otherwise it'll be the element itself.
+      return rootNode && rootNode !== element;
     }
-
-    return this._cachedShadowRoot;
+    // Otherwise fall back to checking if it's in the document. This doesn't account for
+    // shadow DOM, however browser that support shadow DOM should support `getRootNode` as well.
+    return document.documentElement!.contains(element);
   }
 }