addressed comments

Author: mmalerba

src/lib/core/datetime/native-date-adapter.spec.ts

@@ -304,6 +304,14 @@ describe('NativeDateAdapter', () => {
       expect(adapter.format(new Date(1800, 7, 14), {day: 'numeric'})).toBe('Thu Aug 14 1800');
     }
   });
+
+  it('should count a Date as a date object', () => {
+    expect(adapter.isDateObject(new Date())).toBe(true);
+  });
+
+  it('should not count a string as a date object', () => {
+    expect(adapter.isDateObject('1/1/2017')).toBe(false);
+  });
 });
 
 

src/lib/datepicker/datepicker-input.ts

@@ -117,7 +117,7 @@ export class MdDatepickerInput<D> implements AfterContentInit, ControlValueAcces
   }
   set value(value: D | null) {
     if (value != null && !this._dateAdapter.isDateObject(value)) {
-      throw new Error('Datepicker: value not recognized as a date object by DateAdapter.');
+      throw Error('Datepicker: value not recognized as a date object by DateAdapter.');
     }
     let oldDate = this.value;
     this._renderer.setProperty(this._elementRef.nativeElement, 'value',