feat(compiler): implement "enableIvy" compiler option (#21427)

The "enableIvy" compiler option is the initial implementation
of the Render3 (or Ivy) code generation. This commit enables
generation generating "Hello, World" (example in the test)
but not much else. It is currenly only useful for internal Ivy
testing as Ivy is in development.

PR Close #21427

packages/compiler/src/util.ts

@@ -6,6 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {ConstantPool} from './constant_pool';
+
 import * as o from './output/output_ast';
 import {ParseError} from './parse_util';
 
@@ -90,6 +92,10 @@ export const SyncAsync = {
   }
 };
 
+export function error(msg: string): never {
+  throw new Error(`Internal Error: ${msg}`);
+}
+
 export function syntaxError(msg: string, parseErrors?: ParseError[]): Error {
   const error = Error(msg);
   (error as any)[ERROR_SYNTAX_ERROR] = true;
@@ -152,6 +158,7 @@ export function utf8Encode(str: string): string {
 export interface OutputContext {
   genFilePath: string;
   statements: o.Statement[];
+  constantPool: ConstantPool;
   importExpr(reference: any, typeParams?: o.Type[]|null, useSummaries?: boolean): o.Expression;
 }