feat(@ngtools/webpack): remove importFactories option

It will just be always be used when applicable.

packages/ngtools/webpack/src/angular_compiler_plugin.ts

@@ -94,7 +94,6 @@ export class AngularCompilerPlugin {
   private _moduleResolutionCache: ts.ModuleResolutionCache;
   private _resourceLoader?: WebpackResourceLoader;
   private _discoverLazyRoutes = true;
-  private _importFactories = false;
   private _useFactories = false;
   // Contains `moduleImportPath#exportName` => `fullModulePath`.
   private _lazyRoutes: LazyRouteMap = {};
@@ -283,11 +282,6 @@ export class AngularCompilerPlugin {
       this._useFactories = true;
     }
 
-    if (this._useFactories && options.importFactories === true) {
-      // Only transform imports to use factories with View Engine.
-      this._importFactories = true;
-    }
-
     // Default ContextElementDependency to the one we can import from here.
     // Failing to use the right ContextElementDependency will throw the error below:
     // "No module factory available for dependency type: ContextElementDependency"
@@ -931,7 +925,8 @@ export class AngularCompilerPlugin {
       // Remove unneeded angular decorators.
       this._transformers.push(removeDecorators(isAppPath, getTypeChecker));
       // Import ngfactory in loadChildren import syntax
-      if (this._importFactories) {
+      if (this._useFactories) {
+        // Only transform imports to use factories with View Engine.
         this._transformers.push(importFactory(msg => this._warnings.push(msg)));
       }
     }

packages/ngtools/webpack/src/interfaces.ts

@@ -49,7 +49,6 @@ export interface AngularCompilerPluginOptions {
   // When using Ivy, the string syntax is not supported at all. Thus we shouldn't attempt that.
   // This option is also used for when the compilation doesn't need this sort of processing at all.
   discoverLazyRoutes?: boolean;
-  importFactories?: boolean;
 
   // added to the list of lazy routes
   additionalLazyModules?: { [module: string]: string };