Early out if the scroll position passed in by js is NaN

Source/core/frame/LocalDOMWindow.cpp

Index: Source/core/frame/LocalDOMWindow.cpp
diff --git a/Source/core/frame/LocalDOMWindow.cpp b/Source/core/frame/LocalDOMWindow.cpp
index e347ad1045eab396af17f553cea46caed05003b3..ba71b696fec14db2950c40b93a66d70a598518d5 100644
--- a/Source/core/frame/LocalDOMWindow.cpp
+++ b/Source/core/frame/LocalDOMWindow.cpp
@@ -1380,6 +1380,9 @@ void LocalDOMWindow::scrollBy(double x, double y, ScrollBehavior scrollBehavior)
     if (!view)
         return;
 
+    if (std::isnan(x) || std::isnan(y))
+        return;

[Rick Byers, 2014/10/21 22:22:33]

You said the previous behavior was to scroll to 0, is that right?  Or did it
actually ignore the scroll?  Either is probably OK - just want to understand
your thinking here.

[Yufeng Shen (Slow to review), 2014/10/21 22:49:31]

Yeah, I changed my mind and felt that ignore the nan scroll position is more
reasonable. It is also consistent with how Element.setScrollLeft/Top handles
nan. 

+
     DoubleSize scaledOffset(x * m_frame->pageZoomFactor(), y * m_frame->pageZoomFactor());
     view->scrollBy(scaledOffset, scrollBehavior);
 }
@@ -1403,6 +1406,9 @@ void LocalDOMWindow::scrollTo(double x, double y, ScrollBehavior scrollBehavior)
     if (!view)
         return;
 
+    if (std::isnan(x) || std::isnan(y))
+        return;
+
     DoublePoint layoutPos(x * m_frame->pageZoomFactor(), y * m_frame->pageZoomFactor());
     view->setScrollPosition(layoutPos, scrollBehavior);
 }