Refactoring on exploreReducer.js

[hughhhh]

Changed return statement to have es6 syntax insteas of Object.assign() function call

@betodealmeida @mistercrunch

[mistercrunch]

I'm not sure if this line is right, shouldn't this be controls: just controls, ?

[mistercrunch]

Is this right?

[hughhhh]

Reference ^^ above comments

[mistercrunch]

Please fix the build failure and merge conflict.

[codecov-io]

Codecov Report

Merging #4836 into master will increase coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4836      +/-   ##
==========================================
+ Coverage   76.91%   76.96%   +0.04%     
==========================================
  Files          44       44              
  Lines        8522     8534      +12     
==========================================
+ Hits         6555     6568      +13     
+ Misses       1967     1966       -1

Impacted Files	Coverage Δ
superset/connectors/sqla/models.py	74.23% <0%> (-1.18%)	⬇️
superset/utils.py	88.06% <0%> (-0.04%)	⬇️
superset/views/core.py	74.68% <0%> (+0.03%)	⬆️
superset/models/core.py	86.54% <0%> (+0.04%)	⬆️
superset/viz.py	79.87% <0%> (+0.54%)	⬆️

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[hughhhh]

I was following the same pattern for the Object.assign which is merging state and controls together. I've refactored it using the spread operator notation.

> a
{ foo: 'bar' }
> b
{ hugh: 'miles' }
> {...a, ...b}
{ foo: 'bar', hugh: 'miles' }

[mistercrunch]

From my understanding this will spread the content of controls into the root of state. Meaning if I translate your current statement here into the pre-ES6 notation I'll get Object.assign({}, state, controls); which is different from Object.assign({}, state, { controls });, we want the controls to go under state.controls, not in the root of state

[mistercrunch]

LGTM