Bug 1361749: Remove unused empty constructor of ScrollbarStyles. r=mats

MozReview-Commit-ID: 6UHSSr4Imiu
Signed-off-by: Emilio Cobos Álvarez <emilio@crisal.io>

layout/base/ScrollbarStyles.h

@@ -52,7 +52,6 @@ struct ScrollbarStyles
 
   explicit ScrollbarStyles(const nsStyleDisplay* aDisplay);
   ScrollbarStyles(uint8_t aH, uint8_t aV, const nsStyleDisplay* aDisplay);
-  ScrollbarStyles() {}
   bool operator==(const ScrollbarStyles& aStyles) const {
     return aStyles.mHorizontal == mHorizontal && aStyles.mVertical == mVertical &&
            aStyles.mScrollBehavior == mScrollBehavior &&