fix(AST): `TemplateAstVisitor.visitContainer()` now visits child nodes
fix(AST): `TemplateAstVisitor.visitContainer()` now visits child nodes

The makes the behavior of visiting all standalone AST types consistent.

PiperOrigin-RevId: 195309157

matanlurey/angular,angulardart/angular,angulardart/angular,chalin/angular2,angulardart/angular,chalin/angular2,chalin/angular2,matanlurey/angular,matanlurey/angular