Do not set value on float overflow

[huww98]

This is consistent with int overflow and json v1

[dsnet]

Hi, thanks for the contribution. We're still doing widescale regression testing and we may or may not do this. v1 is already inconsistent with itself, so is not necessarily the best model to follow.

[huww98]

Thanks for your reply. My largest concern is exposing the math.MaxFloat64 to user (golang/go#63397 (comment)), this can be confusing, or even incorrect in some cases. And apart from v1, this is also consistent with v2 int overflow behavior:

json/arshal_test.go

Lines 5103 to 5107 in 7564cc5

	name: jsontest.Name("Ints/Int64/MaxOverflow"),
	inBuf: `9223372036854775808`,
	inVal: addr(int64(-1)),
	want: addr(int64(-1)),
	wantErr: EU(strconv.ErrRange).withVal(`9223372036854775808`).withType('0', T[int64]()),