fix(overlay): restore previous host element before attaching

Author: dirkluijk

src/cdk/overlay/overlay-ref.ts

@@ -114,15 +114,15 @@ export class OverlayRef implements PortalOutlet, OverlayReference {
   attach(portal: Portal<any>): any {
     let attachResult = this._portalOutlet.attach(portal);
 
-    if (this._positionStrategy) {
-      this._positionStrategy.attach(this);
-    }
-
     // Update the pane element with the given configuration.
     if (!this._host.parentElement && this._previousHostParent) {
       this._previousHostParent.appendChild(this._host);
     }
 
+    if (this._positionStrategy) {
+      this._positionStrategy.attach(this);
+    }
+
     this._updateStackingOrder();
     this._updateElementSize();
     this._updateElementDirection();