Main method not called using ddc

* Dart SDK Version (`dart --version`) `Dart SDK version: 2.12.0-29.10.beta`, `Dart SDK version: 2.10.4` - tested using these dart sdks.

* Whether you are using Windows, MacOSX, or Linux (if applicable) - macOS Catalina, 10.15.7
* Whether you are using Chrome, Safari, Firefox, Edge (if applicable)- tested in all browsers, including safari and Firefox. Chrome version = 87.0.4
* Package **webdev** is currently active at version **2.7.1.**

**main.dart** has following code:

```
import 'package:angular/angular.dart';
import 'package:angular_router/angular_router.dart';
import 'main.template.dart' as self;
import 'package:company/app_component.template.dart' as ng;

@GenerateInjector([
routerProvidersHash,
])
final InjectorFactory injector = self.injector$Injector;

void main() {
print(" in main 25 "); // main method never executed
runApp(ng.AppComponentNgFactory, createInjector: injector); // this line never executed, neither
}
```

**app_component.dart**:

```
import 'package:angular/angular.dart';
import 'package:angular_router/angular_router.dart';

@Component(
selector: 'infapp',
templateUrl: 'app_component.html',
directives: const [
coreDirectives,
routerDirectives,
],
)
class AppComponent {
AppComponent(Router router) {
print("AppComponent called ... "); // never executed
}
}
```
**app_component.html**

`

I should see this ...

`

**index.html**:
```

company

(function () {
var m = document.location.pathname.match(/^(\/[-\w]+)+\/web($|\/)/);
document.write('<base href="' + (m ? m[0] : '/') + '" />');
}());

```

**pubsec.yaml**

```
name: company
description: company
version: 0.0.1
environment:
sdk: '>=2.10.0 <=3.0.0'
dependencies:
angular: ^6.0.1
angular_forms: ^3.0.0
angular_router: ^2.0.0
http: ^0.12.2
stream_transform: ^1.2.0
uuid: ^2.2.2
json_annotation: ^3.1.0
bootstrap_sass: ^4.5.0
angular_components: ^1.0.2
dev_dependencies:
sass_builder: ^2.1.3
json_serializable: ^3.5.0
build_runner: ^1.10.9
build_web_compilers: ^2.15.1
```

Command used to run the app with ddc compiler:
`pub global run webdev serve --debug -v`

It compiles fine, no errors, but when navigating to http://localhost:8080, only index.html content is displayed, AppComponent component never instantiated, nor main method of main.dart called . Only one warning in a chrome developer console:

`DevTools failed to load SourceMap: Could not load content for http://127.0.0.1:8080/packages/build_web_compilers/src/dev_compiler_stack_trace/stack_trace_mapper.dart.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE`

When running dart2js compiler, app behaves correctly, and AppComponent is loaded:
`pub global run webdev serve --release -v`

As another example, I have tested this issue with sample TOH at: https://github.com/angular-examples/quickstart/tree/master too

After fixing few dependencies, app could build, not able to run it with ddc compiler, only with dart2js.

**Note**: There is no **build.yaml** in a project sources.

1) Why is main.dart main method never executes ?
2) Why is AppComponent constructor never gets called ?
3) What am I doing wrong ? :)

Thank you

Start with main.dart and index.html, then compare the generated main.dart.js when using `pub global run webdev serve --debug -v` versus `--release -v`. Check the browser console and the referenced Angular quickstart reproduction. Done means DDC invokes main(), constructs AppComponent, and renders its template.

Written by the indexing model from the issue text.