fix(animations): treat numeric state name values as strings (#22923)

This patch ensures that if a numeric state name value in an animation
is detected then it will not throw an error. Normally this wouldn't
occur, but some JS optimizers may convert a quoted numeric value
(like "1" to 1) in some cases to save space. This patch makes sure
that Angular doesn't throw an error when this occurs.

PR Close #22923

packages/animations/browser/src/dsl/animation_ast_builder.ts

@@ -96,7 +96,7 @@ export class AnimationAstBuilderVisitor implements AnimationDslVisitor {
       if (def.type == AnimationMetadataType.State) {
         const stateDef = def as AnimationStateMetadata;
         const name = stateDef.name;
-        name.split(/\s*,\s*/).forEach(n => {
+        name.toString().split(/\s*,\s*/).forEach(n => {
           stateDef.name = n;
           states.push(this.visitState(stateDef, context));
         });