[WIP] Web Animations API: Constructing an Animation from partial keyframes throws a JS exception

LayoutTests/web-animations-api/element-animate-list-of-keyframes.html

Index: LayoutTests/web-animations-api/element-animate-list-of-keyframes.html
diff --git a/LayoutTests/web-animations-api/element-animate-list-of-keyframes.html b/LayoutTests/web-animations-api/element-animate-list-of-keyframes.html
index 4bb195f8db39f61b02b862d739bf1e81e6f311c7..bf64ff9177b91df5b11474bdeda1299734277437 100644
--- a/LayoutTests/web-animations-api/element-animate-list-of-keyframes.html
+++ b/LayoutTests/web-animations-api/element-animate-list-of-keyframes.html
@@ -16,12 +16,14 @@
     <div id='e1' class='anim'></div>
     <div id='e2' class='anim'></div>
     <div id='e3' class='anim'></div>
+    <div id='e4' class='anim'></div>
 </body>
 
 <script>
 var e1 = document.getElementById('e1');
 var e2 = document.getElementById('e2');
 var e3 = document.getElementById('e3');
+var e4 = document.getElementById('e4');
 
 var e1Style = getComputedStyle(e1);
 var e2Style = getComputedStyle(e2);
@@ -64,4 +66,17 @@ test(function() {
     assert_equals(e3Style.backgroundColor, 'rgb(0, 0, 0)');
     assert_equals(e3Style.foo, undefined);
 }, 'Calling animate() with a pre-constructed keyframes list should start an animation. Invalid style declarations should be ignored.');
+
+test(function() {
+    var partialKeyframes1 = [
+        {opacity: '1', color: 'red', offset: 0},
+        {opacity: '0', offset: 1}];
+
+    var partialKeyframes2 = [
+        {opacity: '1', color: 'red', offset: 0},
+        {opacity: '0', color: 'foo', offset: 1}];
+
+    assert_throws('NOT_SUPPORTED_ERR', function() { e4.animate(partialKeyframes1, durationValue); });
+    assert_throws('NOT_SUPPORTED_ERR', function() { e4.animate(partialKeyframes2, durationValue); });
+}, 'Calling animate() with a partial keyframe should throw a NotSupportedError.');
 </script>