[Blink] Don't use bitmap CRP in WebGL's GetImage()

This method calls Snapshot() on the CRP. For the
bitmap provider this is (naturally) an unaccelerated snapshot [1][2]. We
can instead *not* create a BitmapCRP and instead simply generate an
unaccelerated snapshot from the DrawingBuffer directly.

To enable this flow, we add a new
CopyRenderingResultsToUnacceleratedStaticBitmapImage() that takes the
flow for resolving the canvas' contents in [3] and then simply copies
those contents to an unaccelerated static bitmap image, ensuring that
the parameters for the static bitmap image are the same as they were
before:

* N32 and premul [4]
* Top-left [5][6]

[1] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/platform/graphics/canvas_resource_provider.cc;l=178-183?q=CanvasResourceProviderBitmap::Sn&ss=chromium
[2] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/platform/graphics/canvas_resource_provider.cc;l=1735-1741;drc=6426c956fff8675e1be78ba3c70fceb7d2651f18?q=CanvasResourceProviderBitmap::Sn&ss=chromium
[3] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc;l=2128-2139?q=CopyRenderingResults&ss=chromium
[4] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/webgl/webgl_rendering_context_base.cc;l=2176?q=CopyRenderingResultsFrom&ss=chromium
[5] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/platform/graphics/canvas_resource_provider.h;l=184;drc=fd05369b5220d9daae714f450e099d070a841262;bpv=1;bpt=1
[6] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/platform/graphics/image_orientation_enum.h;l=26;drc=fd05369b5220d9daae714f450e099d070a841262;bpv=1;bpt=1

Bug: 352263194
Change-Id: I851c5cff4b7c23d39c8569ea6fbc6224d33ec992
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6790288
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1494649}