Back out Robert O'Callahan's patch from bug 417178 due to mochitest failure.

layout/reftests/bugs/reftest.list

@@ -758,7 +758,6 @@ fails == 413027-3.html 413027-3-ref.html
 == 416752-1.html 416752-1-ref.html
 == 417246-1.html 417246-1-ref.html
 == 417676.html 417676-ref.html
-== 417178-1.html 417178-1-ref.html
 == 418766-1a.html 418766-1-ref.html
 == 418766-1b.html 418766-1-ref.html
 == 419060.html 419060-ref.html

layout/style/nsStyleStruct.h

@@ -306,11 +306,10 @@ struct nsBorderColors {
   }
 };
 
-// Border widths are rounded to the nearest-below integer number of pixels,
-// but values between zero and one device pixels are always rounded up to
-// one device pixel.
+// Border widths are rounded to the nearest integer number of pixels, but values
+// between zero and one device pixels are always rounded up to one device pixel.
 #define NS_ROUND_BORDER_TO_PIXELS(l,tpp) \
-  ((l) == 0) ? 0 : PR_MAX((tpp), (l) / (tpp) * (tpp))
+  ((l) == 0) ? 0 : PR_MAX((tpp), ((l) + ((tpp) / 2)) / (tpp) * (tpp))
 // Outline offset is rounded to the nearest integer number of pixels, but values
 // between zero and one device pixels are always rounded up to one device pixel.
 // Note that the offset can be negative.