Tree handles entities with missing children

test/index.html

@@ -133,6 +133,7 @@
     <script src='../js/id/core/node.js'></script>
     <script src='../js/id/core/relation.js'></script>
     <script src='../js/id/core/way.js'></script>
+    <script src='../js/id/core/tree.js'></script>
 
     <script src='../js/id/connection.js'></script>
 
@@ -172,6 +173,7 @@
     <script src="spec/core/relation.js"></script>
     <script src="spec/core/history.js"></script>
     <script src="spec/core/difference.js"></script>
+    <script src="spec/core/tree.js"></script>
 
     <script src="spec/renderer/background.js"></script>
     <script src="spec/renderer/map.js"></script>

test/spec/core/tree.js

@@ -0,0 +1,18 @@
+describe("iD.Tree", function() {
+    var tree;
+
+    beforeEach(function() {
+        tree = iD.Tree(iD.Graph());
+    });
+
+    describe("intersects", function() {
+        it("excludes entities with missing children, adds them when all are present", function() {
+            var way = iD.Way({id: 'w1', nodes: ['n']});
+            var g = tree.base().replace(way);
+            expect(tree.intersects(iD.geo.Extent([0, 0], [1, 1]), g)).to.eql([]);
+            var node = iD.Node({id: 'n', loc: [0.5, 0.5]});
+            g = tree.base().replace(node);
+            expect(tree.intersects(iD.geo.Extent([0, 0], [1, 1]), g)).to.eql([way, node]);
+        });
+    });
+});