feat: add TypeScript 3 support (#25275)

PR Close #25275

packages/compiler/src/config.ts

@@ -26,7 +26,7 @@ export class CompilerConfig {
         defaultEncapsulation?: ViewEncapsulation,
         useJit?: boolean,
         jitDevMode?: boolean,
-        missingTranslation?: MissingTranslationStrategy,
+        missingTranslation?: MissingTranslationStrategy|null,
         preserveWhitespaces?: boolean,
         strictInjectionParameters?: boolean,
       } = {}) {

packages/compiler/test/template_parser/template_parser_spec.ts

@@ -1137,8 +1137,8 @@ Binding to attribute 'onEvent' is disallowed for security reasons ("<my-componen
 
         function createDir(
             selector: string, {providers = null, viewProviders = null, deps = [], queries = []}: {
-              providers?: CompileProviderMetadata[],
-              viewProviders?: CompileProviderMetadata[],
+              providers?: CompileProviderMetadata[] | null,
+              viewProviders?: CompileProviderMetadata[] | null,
               deps?: string[],
               queries?: string[]
             } = {}): CompileDirectiveSummary {