Mutable exports, i.e. using this pattern
```
export let x = 0;
export function f() {
x += 1;
}
```
is problematic to transpile to CommonJS and Goog.module systems, we are
working on banning it google internal codebase.
The workaround is adding an explcit getter function.
PR Close#32425
- add ng2_switch benchmark to track `ngFor` over `ngSwitch`
- measure create only, createDestroy and update
- simplify the created dom
- always add a style binding
