Depends on #501, #503

Executing change detection using getter stubs (see #501) has two issues.

1. it causes polymorphic calls, which limits the execution speed.
2. it prevents proper tree shaking of dart2js.

To address this instead of generating getters stubs we can generate ChangeDetector class. The changeDetector class is a bit more complicated, but it has significant performance and size impact.

The JS code generation is already working and its implementation can be seen in change_detection_jit_generator.es6 The equivalent dart version needs to be implemented in change_detection_jit_generator.dart.

While in JS we can run the generator at runtime, the dart version needs to execute at transform time.