fix(elements): prevent closure renaming of platform properties (#23843)
fix(elements): prevent closure renaming of platform properties (#23843)

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

gdi2290/angular,angular/angular,wKoza/angular,NathanWalker/angular,alxhub/angular,StephenFluin/angular,mzgol/angular,angular/angular,mgiambalvo/angular,ValtoFrameworks/Angular-2,gdi2290/angular,manekinekko/angular,alxhub/angular,Toxicable/angular,gkalpak/angular,snaptech/angular,jasonaden/angular,mhevery/angular,alxhub/angular,mlaval/angular,ocombe/angular,mzgol/angular,alxhub/angular,ValtoFrameworks/Angular-2,ultrasonicsoft/angular,vicb/angular,mprobst/angular,mgiambalvo/angular,Brocco/angular,gdi2290/angular,IdeaBlade/angular,filipesilva/angular,matsko/angular,snaptech/angular,Toxicable/angular,heathkit/angular,angular-indonesia/angular,gnomeontherun/angular,LucasSloan/angular,mzgol/angular,heathkit/angular,manekinekko/angular,mgol/angular,sarunint/angular,kegluneq/angular,mprobst/angular,brandonroberts/angular,vicb/angular,vikerman/angular,mgechev/angular,trshafer/angular,mgechev/angular,LucasSloan/angular,ultrasonicsoft/angular,snaptech/angular,alexeagle/angular,wKoza/angular,Brocco/angular,jasonaden/angular,alexeagle/angular,mprobst/angular,snaptech/angular,juristr/angular,ocombe/angular,petebacondarwin/angular,vicb/angular,heathkit/angular,jonrimmer/angular,mlaval/angular,LucasSloan/angular,gnomeontherun/angular,hansl/angular,kegluneq/angular,ocombe/angular,vicb/angular,Brocco/angular,angular/angular,jonrimmer/angular,Toxicable/angular,trshafer/angular,JiaLiPassion/angular,mhevery/angular,angular-indonesia/angular,mprobst/angular,jonrimmer/angular,heathkit/angular,mgechev/angular,IdeaBlade/angular,kegluneq/angular,jasonaden/angular,juristr/angular,mzgol/angular,IgorMinar/angular,blesh/angular,matsko/angular,mzgol/angular,hansl/angular,petebacondarwin/angular,manekinekko/angular,jasonaden/angular,IgorMinar/angular,Toxicable/angular,mgiambalvo/angular,kara/angular,IgorMinar/angular,matsko/angular,StephenFluin/angular,jasonaden/angular,NathanWalker/angular,manekinekko/angular,hansl/angular,sarunint/angular,StephenFluin/angular,shairez/angular,kegluneq/angular,hansl/angular,snaptech/angular,shairez/angular,LucasSloan/angular,jonrimmer/angular,manekinekko/angular,petebacondarwin/angular,IdeaBlade/angular,trshafer/angular,Brocco/angular,IgorMinar/angular,LucasSloan/angular,vikerman/angular,mgechev/angular,wKoza/angular,ValtoFrameworks/Angular-2,ocombe/angular,mgechev/angular,mgiambalvo/angular,petebacondarwin/angular,kara/angular,IgorMinar/angular,vikerman/angular,filipesilva/angular,jonrimmer/angular,jasonaden/angular,ultrasonicsoft/angular,sarunint/angular,gkalpak/angular,manekinekko/angular,petebacondarwin/angular,angular-indonesia/angular,matsko/angular,shairez/angular,mhevery/angular,kara/angular,petebacondarwin/angular,JiaLiPassion/angular,mlaval/angular,ultrasonicsoft/angular,ultrasonicsoft/angular,vicb/angular,alexeagle/angular,brandonroberts/angular,alxhub/angular,mgol/angular,ultrasonicsoft/angular,gdi2290/angular,shairez/angular,mgol/angular,IdeaBlade/angular,ValtoFrameworks/Angular-2,JiaLiPassion/angular,ValtoFrameworks/Angular-2,ocombe/angular,filipesilva/angular,juristr/angular,NathanWalker/angular,angular/angular,mhevery/angular,vikerman/angular,angular-indonesia/angular,hansl/angular,brandonroberts/angular,vikerman/angular,heathkit/angular,Toxicable/angular,gkalpak/angular,mgol/angular,heathkit/angular,blesh/angular,NathanWalker/angular,juristr/angular,hansl/angular,NathanWalker/angular,alexeagle/angular,kara/angular,StephenFluin/angular,mlaval/angular,gdi2290/angular,wKoza/angular,matsko/angular,mzgol/angular,trshafer/angular,mgol/angular,juristr/angular,mhevery/angular,kara/angular,gnomeontherun/angular,gnomeontherun/angular,mlaval/angular,NathanWalker/angular,gkalpak/angular,sarunint/angular,mprobst/angular,blesh/angular,LucasSloan/angular,Toxicable/angular,vikerman/angular,ocombe/angular,IgorMinar/angular,alexeagle/angular,blesh/angular,filipesilva/angular,brandonroberts/angular,trshafer/angular,vicb/angular,IdeaBlade/angular,StephenFluin/angular,kegluneq/angular,JiaLiPassion/angular,brandonroberts/angular,kegluneq/angular,trshafer/angular,mprobst/angular,alexeagle/angular,brandonroberts/angular,Brocco/angular,sarunint/angular,jonrimmer/angular,Brocco/angular,kara/angular,shairez/angular,sarunint/angular,filipesilva/angular,snaptech/angular,juristr/angular,wKoza/angular,blesh/angular,wKoza/angular,mhevery/angular,gdi2290/angular,mgiambalvo/angular,mgol/angular