This change implements a new "scheduler" for WebAssembly using binaryen's asyncify transform.
This is more reliable than the current "coroutines" transform, and works with non-Go code in the call stack.
runtime (js/wasm): handle scheduler nesting
If WASM calls into JS which calls back into WASM, it is possible for the scheduler to nest.
The event from the callback must be handled immediately, so the task cannot simply be deferred to the outer scheduler.
This creates a minimal scheduler loop which is used to handle such nesting.
Implements nearly all of the test logging methods for both T and B
structs. Majority of the code has been copied from:
golang.org/src/testing/testing.go
then updated to match the existing testing.go structure.
Code structure/function/method order mimics upstream.
Both FailNow() and SkipNow() cannot be completely implemented,
because they require an early exit from the goroutine. Instead,
they call Error() to report the limitation.
This incomplete implementation allows more detailed test logging and
increases compatiblity with upstream.