--- a/testing/web-platform/tests/web-animations/interfaces/KeyframeEffect/setTarget.html
+++ b/testing/web-platform/tests/web-animations/interfaces/KeyframeEffect/setTarget.html
@@ -80,10 +80,81 @@ test(function(t) {
   // This makes sure the animation property is changed correctly on new
   // targeted element.
   anim.currentTime = 75 * MS_PER_SEC;
   assert_equals(getComputedStyle(b).marginLeft, '75px',
                 'Value of 2nd target (currently targeted) after ' +
                 'changing the animation current time.');
 }, 'Test setting target from a valid target to another target');
 
+test(function(t) {
+  var anim = createDiv(t).animate([ { marginLeft: '0px' },
+                                    { marginLeft: '-20px' },
+                                    { marginLeft: '100px' },
+                                    { marginLeft: '50px' } ],
+                                  { duration: 100 * MS_PER_SEC,
+                                    spacing: 'paced(margin-left)' });
+
+  anim.effect.target = null;
+
+  var frames = anim.effect.getKeyframes();
+  var slots = frames.length - 1;
+  assert_equals(frames[0].computedOffset, 0.0, '1st frame offset');
+  assert_equals(frames[1].computedOffset, 1.0 / slots, '2nd frame offset');
+  assert_equals(frames[2].computedOffset, 2.0 / slots, '3rd frame offset');
+  assert_equals(frames[3].computedOffset, 1.0, 'last frame offset');
+}, 'Test falling back to distribute spacing mode after setting null target');
+
+test(function(t) {
+  var effect = new KeyframeEffect(null,
+                                  [ { marginLeft: '0px' },
+                                    { marginLeft: '-20px' },
+                                    { marginLeft: '100px' },
+                                    { marginLeft: '50px' } ],
+                                  { duration: 100 * MS_PER_SEC,
+                                    spacing: 'paced(margin-left)' });
+  var frames = effect.getKeyframes();
+  var slots = frames.length - 1;
+  assert_equals(frames[1].computedOffset, 1.0 / slots, '2nd frame offset');
+  assert_equals(frames[2].computedOffset, 2.0 / slots, '3rd frame offset');
+}, 'Test falling back to distribute spacing mode if there is no context ' +
+   'element');
+
+test(function(t) {
+  var div1 = createDiv(t);
+  var div2 = createDiv(t);
+  div1.style.marginLeft = '-20px';
+  div2.style.marginLeft = '-50px';
+  var child1 = document.createElement('div');
+  var child2 = document.createElement('div');
+  div1.appendChild(child1);
+  div2.appendChild(child2);
+  //      body
+  //    /      \
+  //  div1     div2
+  // (-20px)  (-50px)
+  //   |        |
+  // child1   child2
+  var anim = child1.animate([ { marginLeft: '0px' },
+                              { marginLeft: 'inherit' },
+                              { marginLeft: '100px' },
+                              { marginLeft: '50px' } ],
+                            { duration: 100 * MS_PER_SEC,
+                              spacing: 'paced(margin-left)' });
+
+  var frames = anim.effect.getKeyframes();
+  var cumDist = [0, 20, 140, 190];
+  assert_equals(frames[1].computedOffset, cumDist[1] / cumDist[3],
+                '2nd frame offset');
+  assert_equals(frames[2].computedOffset, cumDist[2] / cumDist[3],
+                '3rd frame offset');
+
+  anim.effect.target = child2;
+  frames = anim.effect.getKeyframes();
+  cumDist = [0, 50, 200, 250];
+  assert_equals(frames[1].computedOffset, cumDist[1] / cumDist[3],
+                '2nd frame offset after setting a new target');
+  assert_equals(frames[2].computedOffset, cumDist[2] / cumDist[3],
+                '3rd frame offset after setting a new target');
+}, 'Test paced spacing mode after setting a new target');
+
 </script>
 </body>