compile function not working in case of Conv layers.

`FluxJS.compile()` doesn't seem to work when Convolution layers are involved:

```
>>> using Flux
>>> using FluxJS
>>> m = Chain(
Conv((2,2), 1=>16, relu),
x -> maxpool(x, (2,2)),
Conv((2,2), 16=>8, relu),
x -> maxpool(x, (2,2)),
x -> reshape(x, :, size(x, 4)),
Dense(288, 10), softmax)
>>> FLuxJS.compile("mnist",m, rand(10))
Error: StackOverflow
```
The error message is too big.

Start with the shown FluxJS.compile("mnist", m, rand(10)) reproduction using the Chain with Conv and maxpool layers, and reproduce the StackOverflow error. Trace how the Conv layers are handled during compilation; done means this example compiles without StackOverflow and does not produce an excessively large error message.

Written by the indexing model from the issue text.