wgpu crash if scissor rectangle is outside of the window

[s-nie]

It looks like 09d636b introduced the possibility of having a scissor rectangle that is outside of the screen. This leads to a wgpu panic:

ERROR wgpu::backend::direct] Handling wgpu errors as fatal by default
thread 'main' panicked at 'wgpu error: Validation Error

Caused by:
    In a RenderPass
      note: encoder = `encoder`
    In a set_scissor_rect command
    Scissor Rect { x: 1280, y: 720, w: 1, h: 1 } is not contained in the render target Extent3d { width: 1280, height: 720, depth_or_array_layers: 1 }

One way to produce this was to increase the set_pixels_per_point and then on the same frame placing an image in the bottom-right corner. But it also seems to happen in other scenarios.