Closure compiler with type based optimizations has a bug where externs for inherited static fields are not being honored. For Angular Elements this meant that 'observedAttributes' static field which is marked as an extern for the base HTMLElement class was getting renamed.
This commit works around the bug by using quoted access of 'observedAttributes' that explicitly prevents the renaming.
PR Close#23843
Detect server environment by checking `typeof window` and schedule render immediately instead of waiting for RAF.
This does not make Angular Elements work on platform-server. This is just the first step.
PR Close#23324
This PR was merged without API docs and general rollout plan.
We can't release this as is in 5.1 without a plan for documentation, cli integration, etc.