Use empty frame for input when layer bounds is invalid

Fixed a few issues:
1. Return INVALID_RECT for size if there's no buffer for BLAST. This was
already done in BufferQueueLayer. This ensures we don't assume the layer
has a valid size when there's no buffer

2. Don't transform invalid layer bounds in fillInputInfo since it could
result in sending a valid frame when the layer actually has no bounds.
Instead just set input frame to empty, reset the transform, and return
early.

Test: Window with no width or height doesn't get untrusted touch
Test: InputSurfacesTest
Fixes: 173297887
Change-Id: I191d411b0f83ce57b6fdc20a1def8070110d418b