perf(animations): reduce size of bundle by removing AST classes (#19539)

This CL refactors the animation AST code to make use of interfaces instead of classes. Given that interfaces are not persisted during runtime the removal of classes should nicely cut down on size for the animations-browser bundle.

-- before --
animations-browser.umd.js = 222kb
animations-browser.umd.min.js = 107kb

-- after --
animations-browser.umd.js = 213kb
animations-browser.umd.min.js = 102kb

PR Close #19539

packages/animations/browser/src/util.ts

@@ -5,7 +5,9 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
-import {AnimateTimings, AnimationMetadata, AnimationOptions, sequence, ɵStyleData} from '@angular/animations';
+import {AnimateTimings, AnimationMetadata, AnimationMetadataType, AnimationOptions, sequence, ɵStyleData} from '@angular/animations';
+import {Ast as AnimationAst, AstVisitor as AnimationAstVisitor} from './dsl/animation_ast';
+import {AnimationDslVisitor} from './dsl/animation_dsl_visitor';
 
 export const ONE_SECOND = 1000;
 
@@ -232,3 +234,40 @@ export function dashCaseToCamelCase(input: string): string {
 export function allowPreviousPlayerStylesMerge(duration: number, delay: number) {
   return duration === 0 || delay === 0;
 }
+
+export function visitDslNode(
+    visitor: AnimationDslVisitor, node: AnimationMetadata, context: any): any;
+export function visitDslNode(
+    visitor: AnimationAstVisitor, node: AnimationAst<AnimationMetadataType>, context: any): any;
+export function visitDslNode(visitor: any, node: any, context: any): any {
+  switch (node.type) {
+    case AnimationMetadataType.Trigger:
+      return visitor.visitTrigger(node, context);
+    case AnimationMetadataType.State:
+      return visitor.visitState(node, context);
+    case AnimationMetadataType.Transition:
+      return visitor.visitTransition(node, context);
+    case AnimationMetadataType.Sequence:
+      return visitor.visitSequence(node, context);
+    case AnimationMetadataType.Group:
+      return visitor.visitGroup(node, context);
+    case AnimationMetadataType.Animate:
+      return visitor.visitAnimate(node, context);
+    case AnimationMetadataType.Keyframes:
+      return visitor.visitKeyframes(node, context);
+    case AnimationMetadataType.Style:
+      return visitor.visitStyle(node, context);
+    case AnimationMetadataType.Reference:
+      return visitor.visitReference(node, context);
+    case AnimationMetadataType.AnimateChild:
+      return visitor.visitAnimateChild(node, context);
+    case AnimationMetadataType.AnimateRef:
+      return visitor.visitAnimateRef(node, context);
+    case AnimationMetadataType.Query:
+      return visitor.visitQuery(node, context);
+    case AnimationMetadataType.Stagger:
+      return visitor.visitStagger(node, context);
+    default:
+      throw new Error(`Unable to resolve animation metadata node #${node.type}`);
+  }
+}