Fix off-by-one error in RasterShape of CSS shapes

Source/core/rendering/shapes/RasterShape.cpp

Index: Source/core/rendering/shapes/RasterShape.cpp
diff --git a/Source/core/rendering/shapes/RasterShape.cpp b/Source/core/rendering/shapes/RasterShape.cpp
index 2caf3ec295ae952d83a2a57a5013db8ae96e0c08..4f2e6fcd94b68aa96e45a06b7b38bebdf28641b5 100644
--- a/Source/core/rendering/shapes/RasterShape.cpp
+++ b/Source/core/rendering/shapes/RasterShape.cpp
@@ -151,7 +151,10 @@ void RasterShape::getExcludedIntervals(LayoutUnit logicalTop, LayoutUnit logical
     for (int y = y1; y < y2;  y++)
         excludedInterval.unite(intervals.intervalAt(y));
 
-    result.append(LineSegment(excludedInterval.x1(), excludedInterval.x2() + 1));
+    // Note: |marginIntervals()| returns end-point exclusive
+    // intervals. |excludedInterval.x2()| contains the left-most pixel
+    // offset to the right of the calculated union.
+    result.append(LineSegment(excludedInterval.x1(), excludedInterval.x2()));
 }
 
 } // namespace WebCore