Use `table.fill` in externref-xform (`TODO`) #1150

Job	Run time
Rustfmt	12s
Check	3m 48s
Clippy	7m 58s
Run wasm-bindgen crate tests with multithreading enabled	1m 59s
Run wasm-bindgen crate tests (unix)	12m 57s
Build and test the deno example	2m 57s
Run js-sys crate tests	5m 48s
Verify that web-sys is compiled correctly	2m 53s
Run native tests	5m 9s
Test TypeScript output of wasm-bindgen	2m 47s
Run web-sys crate tests	10m 20s
Run wasm-bindgen-webidl crate tests	5m 5s
build_benchmarks	3m 17s
build_nightly	2m 32s
build_examples	5m 50s
dist_linux_aarch64_gnu	5m 29s
dist_linux_x86_64_musl	4m 20s
Run UI compile-fail tests	2m 36s
dist_macos_aarch64	6m 16s
dist_macos_x86_64	8m 27s
dist_windows	8m 4s
doc_api	1m 29s
doc_book	17s
test_examples	4m 41s
deploy	1m 27s
	1h 56m 38s

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