Bug 826305 - Makes .valueAsDate assignment throw if a not a Date nor null is passed. Passing null reset the value. r=bz

content/html/content/src/nsHTMLInputElement.cpp

@@ -1325,9 +1325,15 @@ nsHTMLInputElement::SetValueAsDate(JSContext* aCtx, const jsval& aDate)
     return NS_ERROR_DOM_INVALID_STATE_ERR;
   }
 
+  if (aDate.isNullOrUndefined()) {
+    return SetValue(EmptyString());
+  }
+
+  // TODO: return TypeError when HTMLInputElement is converted to WebIDL, see
+  // bug 826302.
   if (!aDate.isObject() || !JS_ObjectIsDate(aCtx, &aDate.toObject())) {
     SetValue(EmptyString());
-    return NS_OK;
+    return NS_ERROR_INVALID_ARG;
   }
 
   JSObject& date = aDate.toObject();

content/html/content/test/forms/test_valueasdate_attribute.html

@@ -189,9 +189,27 @@ function checkSet()
                                 + data[1]);
   }
 
+  element.value = "test";
   element.valueAsDate = null;
   is(element.value, "", "valueAsDate should set the value to the empty string");
 
+  element.value = "test";
+  element.valueAsDate = undefined;
+  is(element.value, "", "valueAsDate should set the value to the empty string");
+
+  var illegalValues = [
+    "foobar", 42, {}, function() { return 42; }, function() { return Date(); }
+  ];
+
+  for (value of illegalValues) {
+    try {
+      var caught = false;
+      element.valueAsDate = value;
+    } catch(e) {
+      caught = true;
+    }
+    ok(caught, "Assigning " + value + " to .valueAsDate should throw");
+  }
 }
 
 function checkWithBustedPrototype()