form-control-plaintext ignores input-group-$size

Created by: kratsg

Bug reports must include:

• macOS 10.14.6 (18G95)
• Chrome Version 77.0.3865.120 (Official Build) (64-bit)
• Compare the difference here:

<div class="container">
  <div class="row">
    <div class="col">
      <div class="input-group input-group-sm">
        <div class="input-group-prepend">
          <button class="btn btn-primary">Button</button>
        </div>
        <input class="form-control" value="hello world" readonly />
      </div>
    </div>
  </div>
  <div class="row">
    <div class="col">
      <div class="input-group input-group-sm">
        <div class="input-group-prepend">
          <button class="btn btn-primary">Button</button>
        </div>
        <input class="form-control-plaintext" value="hello world" readonly />
      </div>
    </div>
  </div>
</div>

You'll see that the .form-control-plaintext has issues with both width and sizing. The fix is to add .form-control-sm to .form-control-plaintext.