Revert "feat(forms): formControlName also accepts a number (angular#3…

…0606)"

This reverts commit a647298.

packages/forms/src/directives/ng_control.ts

@@ -36,7 +36,7 @@ export abstract class NgControl extends AbstractControlDirective {
    * @description
    * The name for the control
    */
-  name: string|number|null = null;
+  name: string|null = null;
 
   /**
    * @description

packages/forms/src/directives/reactive_directives/form_control_name.ts

@@ -145,13 +145,9 @@ export class FormControlName extends NgControl implements OnChanges, OnDestroy {
    * @description
    * Tracks the name of the `FormControl` bound to the directive. The name corresponds
    * to a key in the parent `FormGroup` or `FormArray`.
-   * Accepts a name as a string or a number.
-   * The name in the form of a string is useful for individual forms,
-   * while the numerical form allows for form controls to be bound
-   * to indices when iterating over controls in a `FormArray`.
    */
   // TODO(issue/24571): remove '!'.
-  @Input('formControlName') name !: string | number | null;
+  @Input('formControlName') name !: string;
 
   /**
    * @description
@@ -242,9 +238,7 @@ export class FormControlName extends NgControl implements OnChanges, OnDestroy {
    * Returns an array that represents the path from the top-level form to this control.
    * Each index is the string name of the control on that level.
    */
-  get path(): string[] {
-    return controlPath(this.name == null ? this.name : this.name.toString(), this._parent !);
-  }
+  get path(): string[] { return controlPath(this.name, this._parent !); }
 
   /**
    * @description

packages/forms/src/directives/shared.ts

@@ -28,8 +28,8 @@ import {SelectMultipleControlValueAccessor} from './select_multiple_control_valu
 import {AsyncValidator, AsyncValidatorFn, Validator, ValidatorFn} from './validators';
 
 
-export function controlPath(name: string | null, parent: ControlContainer): string[] {
-  return [...parent.path !, name !];
+export function controlPath(name: string, parent: ControlContainer): string[] {
+  return [...parent.path !, name];
 }
 
 export function setUpControl(control: FormControl, dir: NgControl): void {

tools/public_api_guard/forms/forms.d.ts

@@ -255,7 +255,7 @@ export declare class FormControlName extends NgControl implements OnChanges, OnD
     readonly formDirective: any;
     isDisabled: boolean;
     /** @deprecated */ model: any;
-    name: string | number | null;
+    name: string;
     readonly path: string[];
     /** @deprecated */ update: EventEmitter<any>;
     readonly validator: ValidatorFn | null;
@@ -353,7 +353,7 @@ export declare const NG_VALUE_ACCESSOR: InjectionToken<ControlValueAccessor>;
 
 export declare abstract class NgControl extends AbstractControlDirective {
     readonly asyncValidator: AsyncValidatorFn | null;
-    name: string | number | null;
+    name: string | null;
     readonly validator: ValidatorFn | null;
     valueAccessor: ControlValueAccessor | null;
     abstract viewToModelUpdate(newValue: any): void;