refactor(compiler): create a new root BindingScope for each template (

#36362)

Previously we had a singleton `ROOT_SCOPE` object, from
which all `BindingScope`s derived. But this caused ngcc to
produce non-deterministic output when running multiple workers
in parallel, since each process had its own `ROOT_SCOPE`.

In reality there is no need for `BindingScope` reference names
to be unique across an entire application (or in the case of ngcc
across all the libraries). Instead we just need uniqueness within
a template.

This commit changes the compiler to create a new root `BindingScope`
each time it compiles a component's template.

Resolves #35180

PR Close #36362

packages/compiler/src/render3/view/compiler.ts

@@ -177,7 +177,7 @@ export function compileComponentFromMetadata(
 
   const template = meta.template;
   const templateBuilder = new TemplateDefinitionBuilder(
-      constantPool, BindingScope.ROOT_SCOPE, 0, templateTypeName, null, null, templateName,
+      constantPool, BindingScope.createRootScope(), 0, templateTypeName, null, null, templateName,
       directiveMatcher, directivesUsed, meta.pipes, pipesUsed, R3.namespaceHTML,
       meta.relativeContextFilePath, meta.i18nUseExternalIds);
 

packages/compiler/src/render3/view/template.ts

@@ -1605,13 +1605,8 @@ export class BindingScope implements LocalResolver {
   private map = new Map<string, BindingData>();
   private referenceNameIndex = 0;
   private restoreViewVariable: o.ReadVarExpr|null = null;
-  private static _ROOT_SCOPE: BindingScope;
-
-  static get ROOT_SCOPE(): BindingScope {
-    if (!BindingScope._ROOT_SCOPE) {
-      BindingScope._ROOT_SCOPE = new BindingScope().set(0, '$event', o.variable('$event'));
-    }
-    return BindingScope._ROOT_SCOPE;
+  static createRootScope(): BindingScope {
+    return new BindingScope().set(0, '$event', o.variable('$event'));
   }
 
   private constructor(public bindingLevel: number = 0, private parent: BindingScope|null = null) {}