Recompute slow scroll regions after overflow recalc

LayoutTests/scrollingcoordinator/non-fast-scrollable-transform-changed-expected.txt

Index: LayoutTests/scrollingcoordinator/non-fast-scrollable-transform-changed-expected.txt
diff --git a/LayoutTests/scrollingcoordinator/non-fast-scrollable-transform-changed-expected.txt b/LayoutTests/scrollingcoordinator/non-fast-scrollable-transform-changed-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..1b39e939199e5121f525bfb9fcd3dedf0590d634
--- /dev/null
+++ b/LayoutTests/scrollingcoordinator/non-fast-scrollable-transform-changed-expected.txt
@@ -0,0 +1,26 @@
+This should be covered by a green overlay.
+A single square should be visible covered by a green overlay.
+
+This test ensures that transforming a non-fast scrollable area correctly updates list of non-fast scrollable rects (See http://crbug.com/417345).
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS nonFastScrollableRects.length is 1
+PASS rectToString(nonFastScrollableRects[0]) is "[0, 0, 222, 222]"
+Trigger style update
+PASS internals.updateStyleAndReturnAffectedElementCount() is 2
+Verifying layout hasn't been triggered
+PASS internals.needsLayoutCount() is 3
+Update non-fast element's transform
+Trigger style update
+PASS internals.updateStyleAndReturnAffectedElementCount() is 1
+Verifying layout still hasn't been triggered
+PASS internals.needsLayoutCount() is 3
+Verifying non-fast regions have been updated
+PASS nonFastScrollableRects.length is 1
+PASS rectToString(nonFastScrollableRects[0]) is "[100, 0, 222, 222]"
+PASS successfullyParsed is true
+
+TEST COMPLETE
+