Removed main-thread one dimensional scrolling paths.

third_party/WebKit/Source/core/dom/Element.cpp

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index 53f79f17c4adc0595dfb52e20d5efb9f1b326e54..017bdc96897aaee6b250ed95487e5220383ab812 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -569,12 +569,13 @@ void Element::nativeApplyScroll(ScrollState& scrollState)
         LayoutBoxItem curBox = LayoutBoxItem(toLayoutBox(layoutObject())).enclosingBox();
         // FIXME: Native scrollers should only consume the scroll they
         // apply. See crbug.com/457765.
-        if (deltaX && curBox.scroll(ScrollLeft, ScrollByPrecisePixel, deltaX).didScroll) {
+        // TODO(bokan): I think the scroll deltas here are backwards.

[skobes, 2016/02/29 18:52:47]

Can you clarify this TODO?  Why are they backwards and where should they be
corrected?

[bokan, 2016/03/01 05:56:24]

Done. (I have a follow up patch which fixes the TODO I'll put up shortly).

+        if (deltaX && curBox.scroll(ScrollByPrecisePixel, FloatSize(-deltaX, 0)).didScrollX) {
             scrollState.consumeDeltaNative(scrollState.deltaX(), 0);
             scrolled = true;
         }
 
-        if (deltaY && curBox.scroll(ScrollUp, ScrollByPrecisePixel, deltaY).didScroll) {
+        if (deltaY && curBox.scroll(ScrollByPrecisePixel, FloatSize(0, -deltaY)).didScrollY) {
             scrollState.consumeDeltaNative(0, scrollState.deltaY());
             scrolled = true;
         }