Merge layer , mode 'dot' implementation

[Afreen F.]

I think the implementation of 'dot' mode for Merge layer ignores the fact that the dot axis can be a tuple too instead of an integer. When a tuple dotAxes is sent as part of attr to Merge layer for dot mode in Merge.js
this.dotAxes = dotAxes <= 0 ? dotAxes : dotAxes - 1 sets this.dotAxes to NaN

[Leon Chen]

Thanks for catching this. Should be fixed now.