FULL PRODUCT VERSION :
java version "1.8.0_31"
Java(TM) SE Runtime Environment (build 1.8.0_31-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.31-b07, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]
Linux gbl05159 2.6.32-220.23.1.el6.x86_64 #1 SMP Tue Jun 12 11:20:15 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux


A DESCRIPTION OF THE PROBLEM :
Dynamically inserted numberic key and values into an initially empty javascript object. Afterwards, a for-in loop is used to enumerate the object key / values. During iteration, however, extra keys are returned that appear to be generated incorrectly by the engine.

e.g., inserted keys 300,100,500,200. The for-in loop returns 300, 100, 101, 102, ... [snip]... ,199,200, 500 instead of just the 4 keys added.


REGRESSION.  Last worked in version 7u65

ADDITIONAL REGRESSION INFORMATION: 
java version "1.7.0_60"
Java(TM) SE Runtime Environment (build 1.7.0_60-b19)
Java HotSpot(TM) 64-Bit Server VM (build 24.60-b09, mixed mode)


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. cd to %JAVA_HOME%/bin
2. jrunscript -f "for-in loop issue.js"


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The last line shows entry count 457
None of the output values should be null
ACTUAL -
The last line showed entry count 9929
Some of the output values are null because the extra keys were not inserted programmatically.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
var orders = {}

var seqs = [
'2126951',
'2126950',
'2128605',
'2128611',
'2128610',
'2122950',
'2122951',
'2129807',
'2129808',
'2128300',
'2128305',
'2128290',
'2128298',
'2128291',
'2128292',
'2127802',
'2127687',
'2127700',
'2127790',
'2128282',
'2128283',
'2016488',
'2107211',
'2126387',
'2126386',
'2126999',
'2126761',
'2124361',
'2127942',
'2126766',
'2128173',
'2128194',
'2128171',
'2128188',
'2128187',
'2128318',
'2128320',
'2128321',
'2128322',
'2128323',
'2127200',
'2127203',
'2127212',
'2127231',
'2127236',
'2128122',
'2128120',
'2128119',
'2127242',
'2126956',
'2126962',
'2126964',
'2127786',
'2127794',
'2127784',
'2126968',
'2120388',
'2120389',
'2120390',
'2126910',
'2124835',
'2126744',
'2124626',
'2126201',
'2129086',
'2129079',
'2129077',
'2129078',
'2129080',
'2126976',
'2128633',
'1881312',
'2126978',
'2126982',
'2126987',
'2126988',
'2126989',
'2126991',
'2126992',
'649387',
'649386',
'649385',
'1757783',
'1757782',
'1757781',
'1757780',
'1757779',
'1693320',
'2127506',
'1757778',
'1757777',
'1757776',
'1757775',
'1757774',
'1757773',
'1757772',
'1757771',
'1757770',
'1757769',
'2100263',
'1757768',
'1757767',
'1757766',
'1757765',
'2105398',
'2126911',
'2122135',
'2124115',
'2126751',
'2126752',
'2124116',
'2126753',
'2126912',
'2126754',
'2077871',
'2122433',
'2039112',
'2027671',
'2127535',
'2025921',
'1825251',
'2127541',
'1790830',
'2037340',
'2128661',
'1381769',
'1373224',
'2118842',
'1727516',
'2020758',
'2126407',
'667195',
'932000',
'740104',
'1202590',
'1408076',
'1408075',
'1656470',
'2127549',
'2127550',
'2127552',
'2127553',
'2127554',
'2127555',
'2127556',
'2127557',
'2127558',
'2127559',
'2127560',
'2127562',
'2127563',
'2127564',
'2127565',
'2127566',
'1702638',
'2127567',
'2127568',
'2127569',
'2127570',
'2127572',
'2127573',
'2127574',
'1672881',
'2127577',
'2127576',
'2127578',
'2127579',
'2127580',
'2127582',
'2127581',
'1920874',
'2127584',
'2127583',
'2127585',
'2127587',
'2127586',
'2127588',
'1900257',
'2127591',
'2127589',
'2127590',
'1680074',
'2127592',
'2127595',
'2039146',
'2127593',
'2127594',
'2127596',
'2127598',
'2127597',
'2127599',
'2127600',
'2127602',
'1955223',
'2127601',
'2127603',
'2127604',
'2127605',
'2127606',
'2127608',
'2127607',
'2048963',
'2127609',
'2127610',
'2127612',
'2054914',
'1900265',
'2127611',
'2020830',
'2025891',
'2043873',
'2127614',
'2127615',
'2127616',
'2047380',
'2043872',
'2098455',
'2127617',
'2127618',
'2127619',
'2127620',
'1997401',
'2043939',
'2098454',
'2127621',
'2047379',
'2098453',
'2047376',
'2127622',
'2127623',
'2048945',
'2100207',
'2102080',
'2127624',
'2118675',
'2127625',
'2084859',
'2084860',
'2127626',
'2127627',
'2095035',
'2095034',
'2118674',
'2105443',
'2116668',
'2118673',
'2127628',
'2105434',
'2105435',
'2107236',
'2118672',
'2127630',
'2116598',
'2103787',
'2103674',
'2083334',
'2111424',
'2112426',
'2103791',
'2116516',
'2120409',
'2112548',
'2114628',
'2114807',
'2110603',
'2110602',
'2114627',
'2109419',
'2109418',
'2114400',
'2114399',
'2125914',
'2120507',
'2126419',
'2124183',
'2124421',
'2126420',
'2122287',
'2122288',
'2124185',
'2127642',
'2127640',
'2127641',
'2126421',
'2124238',
'2124181',
'2126417',
'2127783',
'2126510',
'2126199',
'2127644',
'2121136',
'2126368',
'2126369',
'2126783',
'2126382',
'2126287',
'2126514',
'2127648',
'2127650',
'2116597',
'2126109',
'2126628',
'2127658',
'2126010',
'2126052',
'2127660',
'2127661',
'2127662',
'2119089',
'2127664',
'2125899',
'1910126',
'2107209',
'2107210',
'2126051',
'2124878',
'2126053',
'1789645',
'2127676',
'1561829',
'2123998',
'2126416',
'1819869',
'2127678',
'1790815',
'2124879',
'2127679',
'2127681',
'1750135',
'2122284',
'1807721',
'2127683',
'2127684',
'2127686',
'1850390',
'1970186',
'1767772',
'1535806',
'2127696',
'2127697',
'2126283',
'2127701',
'2127712',
'2127713',
'2127729',
'2129817',
'2127788',
'2127798',
'2127801',
'2126718',
'2126974',
'2128575',
'2128576',
'1328310',
'2129813',
'2129811',
'2129815',
'2127127',
'1867570',
'2127156',
'2127157',
'1867569',
'2127172',
'1957543',
'1957544',
'1957545',
'1957546',
'2127196',
'2127198',
'1542539',
'1674915',
'2126027',
'2126028',
'2127256',
'2127063',
'2122856',
'2122857',
'1787052',
'2127328',
'2127330',
'1935894',
'2127793',
'2118736',
'2128714',
'2128713',
'2127804',
'2126058',
'2129725',
'2129723',
'2129724',
'2126884',
'2127803',
'2118728',
'2107204',
'2127800',
'2110768',
'1900263',
'1481565',
'1361706',
'1668420',
'1894388',
'2126768',
'2122818',
'2129729',
'2129728',
'2129730',
'2102375',
'2037963',
'1414970',
'2127426',
'2127432',
'1926640',
'1961274',
'2112802',
'2100463',
'2114944',
'2114945',
'2124119',
'2105979',
'2122734',
'2122735',
'2114942',
'2114943',
'2114559',
'2115452',
'2126812',
'2124351',
'2126064',
'2100904',
'2126816',
'2127479',
'2126791',
'1181223',
'2126682',
'2126808',
'1926628',
'1926629',
'429972',
'2124343',
'1877405',
'2126804',
'1926630',
'1581491',
'1164064',
'2126799',
'2028000',
'2106244',
'1926634',
'1926633',
'1926636',
'1926635',
'2100826',
'2126806',
'2056761',
'439445',
'1926638'
]

for (var i = 0; i < seqs.length; i++) {
    orders[seqs[i]] = 'order' + seqs[i]
}

var count = 0;
for (var a in orders) {
    count++;
    println(a + " -> " + orders[a]);
}
println('entry count: ' + count);

---------- END SOURCE ----------