Extend invalid size context loss and restore to OffscreenCanvas

HTMLCanvasElement has a mechanism for triggering a context loss if the
canvas size is invalid. OffscreenCanvas doesn't have this.
OffscreenCanvas however are subject to the same canvas limit size.
The OffscreenCanvas is undrawable if is_valid_size_ is false [1], which
is a shorthand for IsValidImageSize [2] [3], same as what
HTMLCanvasElement uses [4].

By enabling the context loss and restore logic for OffscreenCanvas, we
can move the logic to BaseRenderingContext2D, simplifying the overall
implementation.

The test OffscreenCanvas-convertToBlob-oversized.html was failing with
this change. The test validates that that generating large images with
max sizes do not crash. There is a clear size limit for JPEG and WEBP,
but for PNG, a limit of 65535 was used. PNG actually has a much higher
limit. 65535 is actually the limit we put on the canvas size. The CL
adjusts the test to remain under this limit.

[1]: https://crsrc.org/c/third_party/blink/renderer/modules/canvas/offscreencanvas2d/offscreen_canvas_rendering_context_2d.cc;l=288;drc=7334424b6359af19a92dee7da024b6cffc486bb7
[2]: https://crsrc.org/c/third_party/blink/renderer/modules/canvas/offscreencanvas2d/offscreen_canvas_rendering_context_2d.cc;l=106;drc=7334424b6359af19a92dee7da024b6cffc486bb7
[3]: https://crsrc.org/c/third_party/blink/renderer/modules/canvas/offscreencanvas2d/offscreen_canvas_rendering_context_2d.cc;l=192;drc=7334424b6359af19a92dee7da024b6cffc486bb7
[4]: https://crsrc.org/c/third_party/blink/renderer/core/html/canvas/html_canvas_element.cc;l=2145;drc=fcb352f82e1d879fa5b1765254c1de92f570c714

Bug: 404257881
Change-Id: I2bd1632480af674ea628bcc5f8156b8425b55e35
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6414174
Commit-Queue: Jean-Philippe Gravel <jpgravel@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1441270}