Fix whitespace-handling bugs in json-iterator decoder

[tatatodd]

This fixes my unit tests failures.

Note that the existing test suite in go-iterator fails at master, without my changes. Looks like there are related failures in the standard encoding/json package, I haven't dug any deeper.

$ go test ./... ok	github.com/json-iterator/go	5.554s ok	github.com/json-iterator/go/any_tests	5.701s ok	github.com/json-iterator/go/api_tests	5.300s ok	github.com/json-iterator/go/benchmarks	0.694s ok	github.com/json-iterator/go/extension_tests	5.161s ok	github.com/json-iterator/go/extra	5.805s ok	github.com/json-iterator/go/misc_tests	6.473s ok	github.com/json-iterator/go/skip_tests	5.566s --- FAIL: Test_symmetric (0.50s) --- FAIL: Test_symmetric/map[test.stringKeyType]string (0.00s) type_test.go:55: marshal expected: { > "": "{Ħ袴", > "\u003e8ȧ宎軔x宭î\u003e岗Üʎ癮": "%蠂pɨ%y\"憹ʅw", > "A¾員Ç瀍烤ɭĪ銃珚": "璄ę銏C9殝Q橛6駈rD", > "Àɖ\u003c帐埢^¦鯻y睂ƀöɌv滮Ɩř": "Ŧe涴祵#:瓦ƨƼǃ鎠ȼ!囡cg谐綉夻", > "ũɜȃ瘎": "žǺǸ¬%ɯ¹´ǥ", > "ǁ[眧ǩß": "?dǢ煑÷ɒ@索龶ʍ敤骾Ųd5Ƀ緼肐", > "妮ī8羘ɦɍľ": "a\"My罩劇", > "頿Çő": "" } got: { > "MANUAL__": "{Ħ袴", > "MANUAL__\u003e8ȧ宎軔x宭î\u003e岗Üʎ癮": "%蠂pɨ%y\"憹ʅw", > "MANUAL__A¾員Ç瀍烤ɭĪ銃珚": "璄ę銏C9殝Q橛6駈rD", > "MANUAL__Àɖ\u003c帐埢^¦鯻y睂ƀöɌv滮Ɩř": "Ŧe涴祵#:瓦ƨƼǃ鎠ȼ!囡cg谐綉夻", > "MANUAL__ũɜȃ瘎": "žǺǸ¬%ɯ¹´ǥ", > "MANUAL__ǁ[眧ǩß": "?dǢ煑÷ɒ@索龶ʍ敤骾Ųd5Ƀ緼肐", > "MANUAL__妮ī8羘ɦɍľ": "a\"My罩劇", > "MANUAL__頿Çő": "" } obj: (map[test.stringKeyType]string) (len=8) { > (test.stringKeyType) (len=7) "頿Çő": (string) "", > (test.stringKeyType) (len=15) "妮ī8羘ɦɍľ": (string) (len=10) "a\"My罩劇", > (test.stringKeyType) (len=24) "A¾員Ç瀍烤ɭĪ銃珚": (string) (len=23) "璄ę銏C9殝Q橛6駈rD", > (test.stringKeyType) (len=35) "Àɖ<帐埢^¦鯻y睂ƀöɌv滮Ɩř": (string) (len=40) "Ŧe涴祵#:瓦ƨƼǃ鎠ȼ!囡cg谐綉夻", > (test.stringKeyType) (len=27) ">8ȧ宎軔x宭î>岗Üʎ癮": (string) (len=16) "%蠂pɨ%y\"憹ʅw", > (test.stringKeyType) "": (string) (len=6) "{Ħ袴", > (test.stringKeyType) (len=9) "ũɜȃ瘎": (string) (len=17) "žǺǸ¬%ɯ¹´ǥ", > (test.stringKeyType) (len=10) "ǁ[眧ǩß": (string) (len=38) "?dǢ煑÷ɒ@索龶ʍ敤骾Ųd5Ƀ緼肐" } FAIL FAIL	github.com/json-iterator/go/type_tests	1.507s ok	github.com/json-iterator/go/value_tests	5.997s FAIL