[CSS Shapes] Simplify RasterShape implementation

Source/core/rendering/shapes/ShapeInterval.h

Index: Source/core/rendering/shapes/ShapeInterval.h
diff --git a/Source/core/rendering/shapes/ShapeInterval.h b/Source/core/rendering/shapes/ShapeInterval.h
index efeb7d862c0e046e20620aa3df10acb9b2634250..3c2fb368a72a1c4efcfdc50210ab0a2d94fa687c 100644
--- a/Source/core/rendering/shapes/ShapeInterval.h
+++ b/Source/core/rendering/shapes/ShapeInterval.h
@@ -207,6 +207,16 @@ public:
     bool operator==(const ShapeInterval<T>& other) const { return x1() == other.x1() && x2() == other.x2(); }
     bool operator!=(const ShapeInterval<T>& other) const { return !operator==(other); }
 
+    void unite(const ShapeInterval<T>& interval)
+    {
+        if (interval.isEmpty())
+            return;
+        if (isEmpty())
+            set(interval.x1(), interval.x2());
+        else
+            set(std::min<T>(x1(), interval.x1()), std::max<T>(x2(), interval.x2()));
+    }
+
 private:
     T m_x1;
     T m_x2;