fix(perspective_view): make transparency work in Chrome on Windows
fix(perspective_view): make transparency work in Chrome on Windows

Reusing the same WebGLFramebuffer (with separate color buffers) for both the regular rendering pass
and the transparent rendering pass resulted in the second color buffer not being properly written in
Chrome on Windows.  While the exact cause of this is unknown, using a separate Framebuffer solves
the problem.

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