Auto merge of #23868 - asajeffrey:webgl-if-used-on-main-thread-use-directly-do-not-pass-go, r=jdm

When using the WebGL external image API, use sync calls if we happen to be on the WebGL thread

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When using the external image API, use synchronous method calls if we happen to be on the same thread as WebGL.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #23832 hopefully
- [x] These changes do not require tests because it's fixing a deadlock

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