Allow non-small components to be used inside a condensed table

[tomshen]

Environment

• Package version(s): 3.0.1
• Browser and OS versions: Google Chrome 68.0.3440.106, MacOS 10.13.6

Steps to reproduce

<HTMLTable small={true}>
  .
  .
  .
  <Button small={false}>Cancel</Button>
  .
  .
  .
</HTMLTable>

Actual behavior

A small button renders in a condensed table.

Expected behavior

A normally sized button renders in a condensed table.

Possible solutions

• Remove .#{$ns}-small & from https://github.com/palantir/blueprint/blob/develop/packages/core/src/components/button/_button.scss#L76.
• Change .#{$ns}-small on HTMLTable to .#{$ns}-condensed

[giladgray]

Remove .#{$ns}-small &

this exists for <ButtonGroup small> so we cannot remove it. we could change the selector to include a > but then we'd also need to handle the wrapped-in-a-Popover case

[giladgray]

I'd be okay with bringing back condensed though it's gotta be done in a non-breaking way.