Minor improvements to wasm-bindgen-futures #1366

Job	Run time
build_examples	4m 1s
Check	2m 36s
build_nightly	2m 47s
build_benchmarks	1m 32s
Verify that web-sys is compiled correctly	1m 55s
Clippy	4m 12s
dist_linux_aarch64_gnu	4m 11s
dist_linux_x86_64_musl	4m 0s
dist_macos_aarch64	4m 8s
dist_macos_x86_64	3m 9s
dist_windows	4m 8s
doc_api	1m 26s
doc_book	31s
Rustfmt	20s
Build and test the deno example	1m 22s
Run js-sys crate tests	3m 43s
Run native tests	3m 3s
Run wasm-bindgen crate tests with multithreading enabled	2m 13s
Test TypeScript output of wasm-bindgen	2m 43s
Run UI compile-fail tests	3m 20s
Run wasm-bindgen crate tests (unix)	3m 32s
Run web-sys crate tests	3m 46s
Run wasm-bindgen-webidl crate tests	2m 40s
test_examples	1s
deploy	1s
	1h 5m 20s

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