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 2a41ee43d2a4c56f7b6b90aa85d5f2b4ce9e7ebc..6293fbc8b86ae8d9c037b5b6455386a98af2a010 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;