fix learnWord for wasm on Firefox and WebKit

[eagleoflqj]

No description provided.

[wengxt]

what's the root cause?

[eagleoflqj]

Firefox and Safari's JS engine (as well as wasm) implements NaN canonicalization, which is allowing only one specific bit representation of NaN. The following code shows the difference on Chrome and Firefox's console:

const f64 = new Float64Array(1);
const u64 = new BigUint64Array(f64.buffer);

u64[0] = 0x7ff8000000000001n; // NaN #1
const nan1 = f64[0];

u64[0] = 0x7ff8000000000002n; // NaN #2
const nan2 = f64[0];

f64[0] = nan1;
console.log("NaN #1 bits:", u64[0].toString(16));

f64[0] = nan2;
console.log("NaN #2 bits:", u64[0].toString(16));

libime's isValid requires different bit representations of NaN

libime/src/libime/core/datrie.cpp

Lines 73 to 78 in 12b62cb

	static int32_t NO_VALUE() {
	return isGoodNanf() ? decodeValue(std::nanf("1")) : 0x7fc00001;
	}
	static int32_t NO_PATH() {
	return isGoodNanf() ? decodeValue(std::nanf("2")) : 0x7fc00002;
	}

thus works only on Chrome.