Test that PackedArray::fromJSON() accepts objects with valid keys (#1703)

https://jira.mongodb.org/browse/PHPC-2350

Author: jmikola

tests/bson/bson-packedarray-fromJSON-001.phpt

@@ -10,6 +10,8 @@ $tests = [
     '[ 1, 2, 3 ]',
     '[[ 1, 2, 3 ]]',
     '[{ "bar": 1 }]',
+    // JSON objects are accepted iff the keys are valid
+    '{ "0": "foo", "1": "bar" }',
 ];
 
 foreach ($tests as $json) {
@@ -34,4 +36,7 @@ Test [[ 1, 2, 3 ]]
 Test [{ "bar": 1 }]
      0 : 16 00 00 00 03 30 00 0e 00 00 00 10 62 61 72 00  [.....0......bar.]
     10 : 01 00 00 00 00 00                                [......]
+Test { "0": "foo", "1": "bar" }
+     0 : 1b 00 00 00 02 30 00 04 00 00 00 66 6f 6f 00 02  [.....0.....foo..]
+    10 : 31 00 04 00 00 00 62 61 72 00 00                 [1.....bar..]
 ===DONE===