message: fix(positioning): resolve perfomance issue
diff: -import { Injectable, ElementRef, RendererFactory2, Inject, PLATFORM_ID } from '@angular/core';
  +import { Injectable, ElementRef, RendererFactory2, Inject, PLATFORM_ID, NgZone } from '@angular/core';
  import { isPlatformBrowser } from '@angular/common';
  import { positionElements } from './ng-positioning';
  @@ -50,13 +50,16 @@ export class PositioningService {
  private isDisabled = false;
  constructor(
  + ngZone: NgZone,
  rendererFactory: RendererFactory2,
  @Inject(PLATFORM_ID) platformId: number
  ) {
  +
  if (isPlatformBrowser(platformId)) {
  + ngZone.runOutsideAngular(() => {
  this.triggerEvent$ = merge(
  - fromEvent(window, 'scroll'),
  - fromEvent(window, 'resize'),
  + fromEvent(window, 'scroll', { passive: true }),
  + fromEvent(window, 'resize', { passive: true }),
  /* tslint:disable-next-line: deprecation */
  of(0, animationFrameScheduler),
  this.update$$
  @@ -80,6 +83,7 @@ export class PositioningService {
  );
  });
  });
  + });
  }
  }
  