Add infrastructure for partial layouts

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index f5eab234cc88aaae78720d3fbae0385340cf0e2a..e7d74b3fe32bd2606cff0e947142af81e290428b 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -568,7 +568,7 @@ static int adjustForLocalZoom(LayoutUnit value, RenderObject* renderer)
 
 int Element::offsetLeft()
 {
-    document()->updateLayoutIgnorePendingStylesheets();
+    document()->tryPartialUpdateLayoutIgnorePendingStylesheets(renderer());
     if (RenderBoxModelObject* renderer = renderBoxModelObject())
         return adjustForLocalZoom(renderer->pixelSnappedOffsetLeft(), renderer);
     return 0;
@@ -576,7 +576,7 @@ int Element::offsetLeft()
 
 int Element::offsetTop()
 {
-    document()->updateLayoutIgnorePendingStylesheets();
+    document()->tryPartialUpdateLayoutIgnorePendingStylesheets(renderer());
     if (RenderBoxModelObject* renderer = renderBoxModelObject())
         return adjustForLocalZoom(renderer->pixelSnappedOffsetTop(), renderer);
     return 0;
@@ -591,7 +591,7 @@ int Element::offsetWidth()
             return adjustLayoutUnitForAbsoluteZoom(renderer->fixedOffsetWidth(), renderer).round();
     }
 
-    document()->updateLayoutIgnorePendingStylesheets();
+    document()->tryPartialUpdateLayoutIgnorePendingStylesheets(renderer());
     if (RenderBoxModelObject* renderer = renderBoxModelObject())
         return adjustLayoutUnitForAbsoluteZoom(renderer->pixelSnappedOffsetWidth(), renderer).round();
     return 0;
@@ -599,7 +599,7 @@ int Element::offsetWidth()
 
 int Element::offsetHeight()
 {
-    document()->updateLayoutIgnorePendingStylesheets();
+    document()->tryPartialUpdateLayoutIgnorePendingStylesheets(renderer());
     if (RenderBoxModelObject* renderer = renderBoxModelObject())
         return adjustLayoutUnitForAbsoluteZoom(renderer->pixelSnappedOffsetHeight(), renderer).round();
     return 0;