fix(directive): update directive with manual key when lang changes

Fixes #439

Author: ocombe

src/translate.directive.ts

@@ -67,6 +67,9 @@ export class TranslateDirective implements AfterViewChecked, OnDestroy {
                 let key: string;
                 if(this.key) {
                     key = this.key;
+                    if(forceUpdate) {
+                        node.lastKey = null;
+                    }
                 } else {
                     let content = node.textContent.trim();
                     if(content.length) {

tests/translate.directive.spec.ts

@@ -119,15 +119,18 @@ describe('TranslateDirective', () => {
 
     it('should update the DOM when the lang changes', () => {
         expect(fixture.componentInstance.noKey.nativeElement.innerHTML).toEqual('TEST');
+        expect(fixture.componentInstance.withParams.nativeElement.innerHTML).toEqual('TEST');
 
         translate.setTranslation('en', {"TEST": "This is a test"});
         translate.setTranslation('fr', {"TEST": "C'est un test"});
 
         translate.use('en');
         expect(fixture.componentInstance.noKey.nativeElement.innerHTML).toEqual('This is a test');
+        expect(fixture.componentInstance.withParams.nativeElement.innerHTML).toEqual('This is a test');
 
         translate.use('fr');
         expect(fixture.componentInstance.noKey.nativeElement.innerHTML).toEqual("C'est un test");
+        expect(fixture.componentInstance.withParams.nativeElement.innerHTML).toEqual("C'est un test");
     });
 
     // Test (temporarily) disabled as the directive tests manipulate the DOM manually which breaks this test.