Fix premature termination of scroll animations while selecting text.

third_party/WebKit/Source/core/frame/RootFrameViewport.cpp

Index: third_party/WebKit/Source/core/frame/RootFrameViewport.cpp
diff --git a/third_party/WebKit/Source/core/frame/RootFrameViewport.cpp b/third_party/WebKit/Source/core/frame/RootFrameViewport.cpp
index 48e18c43c4b9c8a31e222648a714a666140acf0b..c8edee42c1e03226c44856f5113290888876d6e9 100644
--- a/third_party/WebKit/Source/core/frame/RootFrameViewport.cpp
+++ b/third_party/WebKit/Source/core/frame/RootFrameViewport.cpp
@@ -109,9 +109,8 @@ LayoutRect RootFrameViewport::scrollIntoView(const LayoutRect& rectInContent, co
     LayoutRect viewRectInContent = intersection(visualRectInContent, frameRectInContent);
     LayoutRect targetViewport =
         ScrollAlignment::getRectToExpose(viewRectInContent, rectInContent, alignX, alignY);
-    DoublePoint targetOffset(targetViewport.x(), targetViewport.y());
-
-    setScrollPosition(targetOffset, scrollType, ScrollBehaviorInstant);
+    if (targetViewport != viewRectInContent)
+        setScrollPosition(DoublePoint(targetViewport.x(), targetViewport.y()), scrollType);
 
     // RootFrameViewport only changes the viewport relative to the document so we can't change the input
     // rect's location relative to the document origin.