Bug 258725

In `Color RenderStyle::colorResolvingCurrentColor(CSSPropertyID colorProperty, bool visitedLink) const` we currently return some hardcoded value for border colors:
```
auto result = unresolvedColorForProperty(colorProperty, visitedLink);

if (result.isCurrentColor()) {
    auto borderStyle = [&] {
        switch (colorProperty) {
        case CSSPropertyBorderLeftColor:
            return borderLeftStyle();
        case CSSPropertyBorderRightColor:
            return borderRightStyle();
        case CSSPropertyBorderTopColor:
            return borderTopStyle();
        case CSSPropertyBorderBottomColor:
            return borderBottomStyle();
        default:
            return BorderStyle::None;
        }
    }();

    if (!visitedLink && (borderStyle == BorderStyle::Inset || borderStyle == BorderStyle::Outset || borderStyle == BorderStyle::Ridge || borderStyle == BorderStyle::Groove))
        return { SRGBA<uint8_t> { 238, 238, 238 } };

    return visitedLink ? visitedLinkColor() : color();
}

```

I can't think of any good reason for doing this.

The result can be unexpected for web developers.