[Table] Remove style-propable mixin

[newoga]

This one was tough. A few of these components I refactored a good bit because there were loops in which we were recomputing the same style from getStyles() for each item. I've changed it so getStyles() only gets called once in each render which should help performance.

[alitaheri]

More LOC but a bit more readable 😁

const footerRows = React.Children.map(children, (child, rowNumber) => {
  const newChildProps = {
    displayBorder: false,
    key: `f-${rowNumber}`,
    rowNumber: rowNumber,
    style: Object.assign({}, styles.cell, child.props.style),
  };

  let newDescendants;
  if (adjustForCheckbox) {
    newDescendants = [
      <TableRowColumn key={`fpcb${rowNumber}`} style={{width: 24}} />,
      ...React.Children.toArray(child.props.children),
    ];
  }

  return React.cloneElement(child, newChildProps, newDescendants);
});

[newoga]

Looks good! 👍

[alitaheri]

crap, I forgot the return

[newoga]

I noticed, it's okay 😁. I found another issue with this PR too...

[newoga]

• Made code modifications suggested by @alitaheri to improve code readability ([comment])([Table] Remove style-propable mixin #3227 (comment))
• A few bug fixes

[oliviertassinari]

All good for me 👍.

[alitaheri]

Awesome work @newoga 👍 You're doing a great job 😄