Fixes #17034.

Flash Player has a fairly complicated, implementation-dependent behavior related to degenerate bounds and bounds that change after being highlighted. It seems that the highlight is hidden when there's nothing to be rendered:

1. For a clip with untouched graphics, the highlight is hidden.
2. For a clip with moveTo(0,0) lineTo(0,0), the highlight is not hidden.

Sometimes highlight is not updated after highlight bounds change, but this behavior is rare and inconsistent, it even differs depending on when the update happens.

However, the most common case of depending on the behavior above is when the SWF creates a movie clip, focuses it, and then adds some content to it. In that case FP will not render the highlight (even if in theory it should). Hiding focus highlight on invalid and empty bounds covers this case, but:

1. In some rare cases, it will hide the highlight when it shouldn't (e.g. non-empty graphics degenerated into a point).
2. It does not take into account that sometimes FP does not update highlight bounds.

However, I've never seen these cases in real SWFs, only during testing.