[ruby/json] Reject invalid number: `-` `-.1` `-e0` #579

Job	Run time
omnibus compilations, trigger	4s
omnibus compilations, #1	29m 39s
omnibus compilations, #2	30m 23s
omnibus compilations, #3	26m 8s
omnibus compilations, #8	28m 16s
omnibus compilations, #10	26m 41s
omnibus compilations, #11	26m 6s
omnibus compilations, #9	27m 49s
omnibus compilations, #7	27m 16s
omnibus compilations, #5	26m 39s
omnibus compilations, #6	27m 36s
omnibus compilations, #12	24m 30s
omnibus compilations, #4	26m 23s
omnibus compilations, result	2s
	5h 27m 32s

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