Don't use unit per pixel in ParticleEmitter2D.

Source/Engine/Urho2D/ParticleEmitter2D.cpp

@@ -228,10 +228,10 @@ void ParticleEmitter2D::UpdateVertices()
         float add = (c + s) * p.size_ * 0.5f;
         float sub = (c - s) * p.size_ * 0.5f;
 
-        vertex0.position_ = Vector3(p.position_.x_ - sub, p.position_.y_ - add, zValue_) * unitPerPixel_;
-        vertex1.position_ = Vector3(p.position_.x_ - add, p.position_.y_ + sub, zValue_) * unitPerPixel_;
-        vertex2.position_ = Vector3(p.position_.x_ + sub, p.position_.y_ + add, zValue_) * unitPerPixel_;
-        vertex3.position_ = Vector3(p.position_.x_ + add, p.position_.y_ - sub, zValue_) * unitPerPixel_;
+        vertex0.position_ = Vector3(p.position_.x_ - sub, p.position_.y_ - add, zValue_);
+        vertex1.position_ = Vector3(p.position_.x_ - add, p.position_.y_ + sub, zValue_);
+        vertex2.position_ = Vector3(p.position_.x_ + sub, p.position_.y_ + add, zValue_);
+        vertex3.position_ = Vector3(p.position_.x_ + add, p.position_.y_ - sub, zValue_);
 
         vertex0.color_ = vertex1.color_ = vertex2.color_  = vertex3.color_ = p.color_.ToUInt();