Correct for enclosing layers scroll position in sticky_data->main_thread_offset

third_party/WebKit/LayoutTests/compositing/overflow/composited-sticky-element-enclosing-layers.html

Index: third_party/WebKit/LayoutTests/compositing/overflow/composited-sticky-element-enclosing-layers.html
diff --git a/third_party/WebKit/LayoutTests/compositing/overflow/composited-sticky-element-enclosing-layers.html b/third_party/WebKit/LayoutTests/compositing/overflow/composited-sticky-element-enclosing-layers.html
new file mode 100644
index 0000000000000000000000000000000000000000..e91a0a67d216be50e61c1f1336bb37aa92c3c235
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/composited-sticky-element-enclosing-layers.html
@@ -0,0 +1,33 @@
+<script>
+onload = function() {
+  scroller.scrollTop = 200;
+}
+</script>
+<style>
+.composited {
+  will-change: transform;
+}
+
+#scroller {
+  overflow: scroll;
+  height: 200px;
+  width: 200px;
+}
+
+.container {
+  height: 500px;
+  background: red;
+}
+
+.sticky {
+  position: sticky;
+  top: 25px;
+  height: 50px;
+  background: green;
+}
+</style>
+<div id="scroller" class="composited">
+  <div class="composited container">
+    <div class="composited sticky"></div>
+  </div>
+</div>