Using EditableText in selected tree element leads to unreadable text

Bug report

• Package version(s):

    "@blueprintjs/core": "^2.0.0-rc.2",
    "@blueprintjs/icons": "^2.0.0-rc.2",
    "@blueprintjs/table": "^2.0.0-rc.2",

• Browser and OS versions: Chrome 64.0.3282.186 on OS X

Steps to reproduce

1. Create
2. Add child element with EditableText as label
3. Select element and start editing

Actual behavior

The editable text is unreadable because it's white text on white background.

Expected behavior

Visibly different colors for text and background.

Shouldn't pt.editable-text.pt-editable-editing set the text-color when setting the background-color? Setting only one of them sounds like inviting this kind of problems.