`firstChange` not set properly in `ngOnChanges` for pre-bound properties

🐞 bug report

Affected Package

The issue is caused by package @angular/elements

Is this a regression?

No.

Description

When a property is set on an element prior to it being attached to the DOM, the initial call to ngOnChanges does not have firstChange properties set to true.

This requires code from #36114, to fix #30848 in order for ngOnChanges to fire at all – this is a follow-on issue.

🔬 Minimal Reproduction

https://github.com/antch/angular-elements-lifecycle-hooks You can look at console logs to see lifecycle events for both the Native Angular element, and the Custom Element. The reproduction uses artifacts from a CI build associated with #36114.

There is a secondary issue here, that is – event listeners on component outputs won’t fire during ngOnInit, ngOnChanges, ngAfterViewInit, and ngAfterContentInit. This is in contrast to the native element which does fire the callback during these hooks. You can see this by examining the ul and li elements in each section.

🌍 Your Environment

Angular Version: Warning: This is a build off of CI assets, so this isn’t entirely accurate.

Angular CLI: 9.0.6
Node: 10.14.2
OS: darwin x64

Angular: 9.1.0-next.4
... animations, common, compiler, compiler-cli, core, elements
... forms, language-service, platform-browser
... platform-browser-dynamic, router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.900.6
@angular-devkit/build-angular     0.900.6
@angular-devkit/build-optimizer   0.900.6
@angular-devkit/build-webpack     0.900.6
@angular-devkit/core              9.0.6
@angular-devkit/schematics        9.0.6
@angular/cli                      9.0.6
@ngtools/webpack                  9.0.6
@schematics/angular               9.0.6
@schematics/update                0.900.6
rxjs                              6.5.4
typescript                        3.6.5
webpack                           4.41.2

[antch]

I created #36141 to cover the output events issue. And thank you again, you have no idea how much I appreciate your work on these issues.

[gkalpak]

Thx for reporting this issue(s 😁), @antch 👍

I have a fix for firstChange in #36140. Please create a separate issue for output events not firing, since that is a different issue and needs to be tracked separately.