feat(forms): add easy way to switch between forms modules (#9202)

modules/@angular/forms/src/directives.ts

@@ -0,0 +1,67 @@
+import {Type} from '@angular/core';
+
+import {CheckboxControlValueAccessor} from './directives/checkbox_value_accessor';
+import {DefaultValueAccessor} from './directives/default_value_accessor';
+import {NgControlStatus} from './directives/ng_control_status';
+import {NgForm} from './directives/ng_form';
+import {NgModel} from './directives/ng_model';
+import {NgModelGroup} from './directives/ng_model_group';
+import {NumberValueAccessor} from './directives/number_value_accessor';
+import {RadioControlValueAccessor} from './directives/radio_control_value_accessor';
+import {FormControlDirective} from './directives/reactive_directives/form_control_directive';
+import {FormControlName} from './directives/reactive_directives/form_control_name';
+import {FormGroupDirective} from './directives/reactive_directives/form_group_directive';
+import {FormGroupName} from './directives/reactive_directives/form_group_name';
+import {NgSelectOption, SelectControlValueAccessor} from './directives/select_control_value_accessor';
+import {NgSelectMultipleOption, SelectMultipleControlValueAccessor} from './directives/select_multiple_control_value_accessor';
+import {MaxLengthValidator, MinLengthValidator, PatternValidator, RequiredValidator} from './directives/validators';
+
+export {CheckboxControlValueAccessor} from './directives/checkbox_value_accessor';
+export {ControlValueAccessor} from './directives/control_value_accessor';
+export {DefaultValueAccessor} from './directives/default_value_accessor';
+export {NgControl} from './directives/ng_control';
+export {NgControlStatus} from './directives/ng_control_status';
+export {NgForm} from './directives/ng_form';
+export {NgModel} from './directives/ng_model';
+export {NgModelGroup} from './directives/ng_model_group';
+export {NumberValueAccessor} from './directives/number_value_accessor';
+export {RadioButtonState, RadioControlValueAccessor} from './directives/radio_control_value_accessor';
+export {FormControlDirective} from './directives/reactive_directives/form_control_directive';
+export {FormControlName} from './directives/reactive_directives/form_control_name';
+export {FormGroupDirective} from './directives/reactive_directives/form_group_directive';
+export {FormGroupName} from './directives/reactive_directives/form_group_name';
+export {NgSelectOption, SelectControlValueAccessor} from './directives/select_control_value_accessor';
+export {NgSelectMultipleOption, SelectMultipleControlValueAccessor} from './directives/select_multiple_control_value_accessor';
+export {MaxLengthValidator, MinLengthValidator, PatternValidator, RequiredValidator} from './directives/validators';
+
+
+
+/**
+ *
+ * A list of all the form directives used as part of a `@Component` annotation.
+ *
+ *  This is a shorthand for importing them each individually.
+ *
+ * ### Example
+ *
+ * ```typescript
+ * @Component({
+ *   selector: 'my-app',
+ *   directives: [FORM_DIRECTIVES]
+ * })
+ * class MyApp {}
+ * ```
+ * @experimental
+ */
+export const FORM_DIRECTIVES: Type[] = /*@ts2dart_const*/[
+  NgModel, NgModelGroup, NgForm,
+
+  NgSelectOption, NgSelectMultipleOption, DefaultValueAccessor, NumberValueAccessor,
+  CheckboxControlValueAccessor, SelectControlValueAccessor, SelectMultipleControlValueAccessor,
+  RadioControlValueAccessor, NgControlStatus,
+
+  RequiredValidator, MinLengthValidator, MaxLengthValidator, PatternValidator
+];
+
+export const REACTIVE_FORM_DIRECTIVES: Type[] =
+    /*@ts2dart_const*/[FormControlDirective, FormGroupDirective, FormControlName, FormGroupName];