Remove margin collapsing.

sky/tests/layout/margins.sky

Index: sky/tests/layout/margins.sky
diff --git a/sky/tests/layout/margins.sky b/sky/tests/layout/margins.sky
index 7ff923694722ca9fcf3989ff8f28e00db97e097a..f720072e738f6d2c090794fefdb6c4be2bcd9f29 100644
--- a/sky/tests/layout/margins.sky
+++ b/sky/tests/layout/margins.sky
@@ -1,17 +1,23 @@
 <sky>
   <import src="../resources/check-layout.sky" as="checkLayout" />
   <style>
+  .root {
+    margin: 5px;
+  }
   .child {
     margin: 10px;
     height: 30px;
   }
   </style>
-  <div class="root" data-expected-height="70" data-total-y="10" style="background-color: pink">
-    <div class="child" data-total-y="10" style="background-color: salmon"></div>
-    <div class="child" data-total-y="50" style="background-color: papayawhip"></div>
+  <div class="root" data-expected-height="100" data-total-y="5" style="background-color: pink">
+    <!-- TODO(ojan): These numbers are right, but the test fails because we appear to have
+    broken offsetTop to not include the parent's margin-top. -->
+    <div class="child" data-total-y="15" style="background-color: salmon"></div>
+    <div class="child" data-total-y="65" style="background-color: papayawhip"></div>
   </div>
 
   <script>
     checkLayout('.root');
   </script>
 </sky>
+