Fix hit-testing in the stocks apps when scrolled.

We were not passing the transformed HitTestLocation when we recursed
into child layers, which meant that we wouldn't take transforms
correctly into account when hit testing.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1019723002

engine/core/rendering/RenderBox.cpp

@@ -673,7 +673,7 @@ bool RenderBox::hitTestLayer(RenderLayer* rootLayer, RenderLayer* containerLayer
     for (auto& currentLayer : layers) {
         HitTestResult tempResult(result.hitTestLocation());
         bool localHitLayer = currentLayer->hitTestLayer(rootLayer, layer(), request, tempResult,
-            hitTestRect, hitTestLocation, localTransformState.get(), zOffsetForDescendantsPtr);
+            localHitTestRect, localHitTestLocation, localTransformState.get(), zOffsetForDescendantsPtr);
 
         // If it a rect-based test, we can safely append the temporary result since it might had hit
         // nodes but not necesserily had hitLayer set.

tests/layout/clipping-elementFromPoint-expected.txt

+CONSOLE: unittest-suite-wait-for-done
+CONSOLE: PASS: should hit test toolbar
+CONSOLE: PASS: should hit test toolbar when transformed, but clipped element overlaps
+CONSOLE: 
+CONSOLE: All 2 tests passed.
+CONSOLE: unittest-suite-success
+DONE

tests/layout/clipping-elementFromPoint.sky

+<style>
+toolbar {
+  background: yellow;
+  width: 50px;
+  height: 50px;
+}
+scrollable {
+  overflow: hidden;
+  height: 400px;
+  background: red;
+}
+content {
+  height: 400px;
+  background-color: pink;
+  transform: translateY(-100px);
+}
+</style>
+<toolbar>toolbar</toolbar>
+<scrollable><content>content</content></scrollable>
+<script>
+import "../resources/third_party/unittest/unittest.dart";
+import "../resources/unit.dart";
+
+import "dart:async";
+import "dart:sky";
+
+void main() {
+  initUnit();
+
+  test("should hit test toolbar", () {
+    expect(document.elementFromPoint(10, 10).textContent, equals("toolbar"));
+  });
+
+  test("should hit test toolbar when transformed, but clipped element overlaps", () {
+    document.querySelector("scrollable").style["transform"] = "translate(0, 0)";
+    expect(document.elementFromPoint(10, 10).textContent, equals("toolbar"));
+  });
+}
+</script>