ANGLE-Metal createViewFromBaseToMaxLevel out-of-range NSRange POC
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Target  : macOS, ANGLE-Metal backend (default), GPU process.
Requires: chromium-changes.patch applied (compromised-renderer simulation).

This page only needs to allocate a WebGL2 back buffer.  On macOS+ANGLE-Metal
that back buffer is an IOSurface-backed SharedImage, and the patched
renderer's DrawingBuffer::CreateColorBuffer() injects a single
TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 5) on the
IOSurface-pbuffer-bound SharedImage texture immediately after
BeginSharedImageAccessDirectCHROMIUM.  Inside the GPU process this drives
ANGLE-Metal into:

  TextureMtl::setBaseLevel
    onBaseMaxLevelsChanged   (isImmutableOrPBuffer()==true)
      createViewFromBaseToMaxLevel()
        createMipsView(5, 1)
          [MTLTexture newTextureViewWithPixelFormat:...
                                             levels:NSMakeRange(5,1)
                                             slices:NSMakeRange(0,1)]

on a parent IOSurface MTLTexture with mipmapLevelCount==1.