fix(vdom): boolean properties in native elements

fixes #1899

Author: manucorporat

src/runtime/vdom/set-accessor.ts

@@ -100,7 +100,8 @@ export const setAccessor = (elm: HTMLElement, memberName: string, oldValue: any,
           let n = newValue == null ? '' : newValue;
 
           // Workaround for Safari, moving the <input> caret when re-assigning the same valued
-          if (oldValue == null || (elm as any)[memberName] !== (n = String(n))) {
+          // tslint:disable-next-line: triple-equals
+          if (oldValue == null || (elm as any)[memberName] != n) {
             (elm as any)[memberName] = n;
           }
         } else {

src/runtime/vdom/test/set-accessor.spec.ts

@@ -321,6 +321,15 @@ describe('setAccessor for inputs', () => {
         testStraightForwardAttribute('spellCheck', undefined, undefined);
         testStraightForwardAttribute('spellCheck', null, undefined);
       });
+
+      it ('checked', () => {
+        const inputElm = document.createElement('input');
+        setAccessor(inputElm, 'checked', false, true, false, 0);
+        expect(inputElm.checked).toEqual(true);
+
+        setAccessor(inputElm, 'checked', true, false, false, 0);
+        expect(inputElm.checked).toEqual(false);
+      });
     });
 
     describe('should update when prop is defined', () => {