Use plain int for borders widths when possible

Source/core/style/BorderData.h

Index: Source/core/style/BorderData.h
diff --git a/Source/core/style/BorderData.h b/Source/core/style/BorderData.h
index cc7910a9b8c782caea60f70295319234524f471f..768f36aca64473b88e17ad87f7e800d8d1416833 100644
--- a/Source/core/style/BorderData.h
+++ b/Source/core/style/BorderData.h
@@ -66,28 +66,28 @@ public:
         return false;
     }
 
-    unsigned borderLeftWidth() const
+    int borderLeftWidth() const
     {
         if (!m_image.hasImage() && (m_left.style() == BNONE || m_left.style() == BHIDDEN))
             return 0;
         return m_left.width();
     }
 
-    unsigned borderRightWidth() const
+    int borderRightWidth() const
     {
         if (!m_image.hasImage() && (m_right.style() == BNONE || m_right.style() == BHIDDEN))
             return 0;
         return m_right.width();
     }
 
-    unsigned borderTopWidth() const
+    int borderTopWidth() const
     {
         if (!m_image.hasImage() && (m_top.style() == BNONE || m_top.style() == BHIDDEN))
             return 0;
         return m_top.width();
     }
 
-    unsigned borderBottomWidth() const
+    int borderBottomWidth() const
     {
         if (!m_image.hasImage() && (m_bottom.style() == BNONE || m_bottom.style() == BHIDDEN))
             return 0;