Add RenderObject::needsResizeLayout

Source/core/rendering/RenderBox.h

Index: Source/core/rendering/RenderBox.h
diff --git a/Source/core/rendering/RenderBox.h b/Source/core/rendering/RenderBox.h
index d546a06a66bc5e72f18b50919096123a69aa30e0..55ceeedf772b56975071d1dcf59df3e9fade94d3 100644
--- a/Source/core/rendering/RenderBox.h
+++ b/Source/core/rendering/RenderBox.h
@@ -530,6 +530,14 @@ public:
         return true;
     }
 
+    bool tryLayoutDoingResizeOnly()
+    {
+        // FIXME: For now this is for RenderView only. Needs more verifications before applied to generic objects.
+        ASSERT(isRenderView());
+        // For now what needed to do happens to be the same as tryLayoutDoingPositionedMovementOnly() does.
+        return tryLayoutDoingPositionedMovementOnly();

[Julien - ping for review, 2014/03/21 19:39:10]

I don't think this is fundamentally right to do a positioned movement only.
RenderView is artificially positioned (it's more of an implementation detail)
but it doesn't *move*, it resizes and that's different. Also this won't handle
the following cases:
- vh units.
- positioned objects with a percentage bottom / top.

[Xianzhu, 2014/03/21 20:10:36]

Actually the intent is not to do a position movement. Calling it just because
the things to do happen to be the same: update logical width and height; if
logical width is different, returns false.

To avoid confusion, I can also repeat the code here.
In these cases, before RenderView's tryLayoutDoingResizeOnly() is called, the
objects have been setNeedsLayout() (which also marked the ancestors
setNeedsLayout()). This will cause a normal full layout (after early returning
from trySimplifiedLayout), despite the setNeedsSizeLayout() flag.

The unit test in https://codereview.chromium.org/204813002/ covers these cases.

This is why we need setNeedsResizeLayout(): otherwise during layout we can't
know if the object needs a simple resize, or a full layout triggered by its
descendants.

+    }
+
     LayoutRect maskClipRect();
 
     virtual PositionWithAffinity positionForPoint(const LayoutPoint&) OVERRIDE;