Fix border radius on composited children.

third_party/WebKit/LayoutTests/compositing/overflow/siblings-with-border-radius-ancestor.html

Index: third_party/WebKit/LayoutTests/compositing/overflow/siblings-with-border-radius-ancestor.html
diff --git a/third_party/WebKit/LayoutTests/compositing/overflow/siblings-with-border-radius-ancestor.html b/third_party/WebKit/LayoutTests/compositing/overflow/siblings-with-border-radius-ancestor.html
new file mode 100644
index 0000000000000000000000000000000000000000..c2f7e4afbf9fc253bb975113c15196a4bdaf7e78
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/siblings-with-border-radius-ancestor.html
@@ -0,0 +1,36 @@
+<style>
+.outermost {
+  border: 4px solid #000;
+  border-radius: 40px;
+  width: 200px;
+  height: 200px;
+  overflow: hidden;
+}
+
+.inner1 {
+  background-color: green;
+  width: 10px;
+  height: 260px;
+  position: relative;
+  left: 0px;
+  top: -30px;
+  will-change: transform;
+}
+
+.inner2 {
+  background-color: green;
+  width: 10px;
+  height: 260px;
+  position: relative;
+  left: 190px;
+  top: -30px;
+}
+</style>
+
+<div class="outermost">
+  <div class="inner1">
+    <div class="inner2">
+    </div>
+  </div>
+</div>
+