Don't allow negative width for positioned elements

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index ef86f2943fdc59b3cad488d411f7f2720369d011..0ad8c3cbc048633237d212948fca39720983cd32 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -3302,6 +3302,8 @@ void RenderBox::computePositionedLogicalWidthUsing(Length logicalWidth, const Re
             computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
         }
     }
+    if (computedValues.m_extent < 0)

[mstensho (USE GERRIT), 2014/09/17 11:48:22]

Might consider moving this to "RULE 5" a few lines further up. Then it will look
more similar to the code in RenderBox::computePositionedLogicalHeightUsing()
(which already has code to avoid negative height).

[Kyungtae Kim, 2014/09/18 12:50:07]

Done.

+        computedValues.m_extent = 0;
 
     // Use computed values to calculate the horizontal position.