fix: allow constant values of infininitesimal non-zero floating points #1877

Job	Run time
build (1.20.x, GOARCH=amd64 GOOS=linux, gno)	17s
test (1.20.x, _test.cmd)	49s
build (1.20.x, GOARCH=wasm GOOS=js, gno)	35s
test (1.20.x, _test.pkg)	43s
build (1.21.x, GOARCH=amd64 GOOS=linux, gno)	52s
test (1.20.x, _test.gnolang.native)	22s
build (1.21.x, GOARCH=wasm GOOS=js, gno)	15s
test (1.20.x, _test.gnolang.stdlibs)	1m 15s
test (1.20.x, _test.gnolang.realm)	30s
test (1.20.x, _test.gnolang.pkg0)	2m 4s
test (1.20.x, _test.gnolang.pkg1)	7m 52s
test (1.20.x, _test.gnolang.pkg2)	5m 7s
test (1.20.x, _test.gnolang.other)	21s
test (1.21.x, _test.cmd)	1m 27s
test (1.21.x, _test.pkg)	1m 20s
test (1.21.x, _test.gnolang.native)	1m 8s
test (1.21.x, _test.gnolang.stdlibs)	1m 57s
test (1.21.x, _test.gnolang.realm)	1m 10s
test (1.21.x, _test.gnolang.pkg0)	2m 15s
test (1.21.x, _test.gnolang.pkg1)	7m 53s
test (1.21.x, _test.gnolang.pkg2)	5m 36s
test (1.21.x, _test.gnolang.other)	1m 3s
upload-coverage	11s
	45m 2s

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