Paint local background colors onto foreground layer.

third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-local-background-expected.html

Index: third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-local-background-expected.html
diff --git a/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-local-background-expected.html b/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-local-background-expected.html
new file mode 100644
index 0000000000000000000000000000000000000000..22b89048669356b6be635aa86241da1109c9596d
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/overflow-scroll-with-local-background-expected.html
@@ -0,0 +1,22 @@
+<script>
+onload = function() {
+    document.getElementById('scroller').scrollTo(0, 200);
+}
+</script>
+<style>
+#scroller {
+    background: gray local content-box;
+    border: 10px solid rgba(0, 255, 0, 0.5);
+    overflow: scroll;
+    padding: 10px;
+    width: 200px;
+    height: 200px;
+}
+
+.spacer {
+    height: 300px;
+}
+</style>
+<div id="scroller">

[chrishtr, 2016/08/08 21:16:39]

Add a comment explaining what this is testing.

[flackr, 2016/08/09 18:35:27]

Done.

+    <div class="spacer"></div>
+</div>