Add nested-nested test.

Taken from Glasser's old code-review.

packages/minimongo/minimongo_tests.js

@@ -1116,6 +1116,12 @@ Tinytest.add("minimongo - fetch with projection, subarrays", function (test) {
                       setA: [{fieldB:33}, {fieldB:"the bad",fieldC:"the ugly"}],
                       setB: [{ anotherB: "meh" }, { anotherB: 431 }]
                     });
+
+  c.remove({});
+  c.insert({a:[[{b:1,c:2},{b:2,c:4}],{b:3,c:5},[{b:4, c:9}]]});
+
+  testForProjection({ 'a.b': 1, _id: 0 },
+                    {"a" : [  [  {  "b" : 1 },  {  "b" : 2 } ],  {  "b" : 3 },  [  {  "b" : 4 } ] ] });
 });
 
 Tinytest.add("minimongo - observe ordered with projection", function (test) {