Replace tree_expand_hidden.html with Intern unit test

This tests expansion of a parent row in a tree grid when it is not in
document flow.  Prior to 0.3.1, the children would expand but be rendered
with 0 height in browsers supporting CSS transitions.

test/data/index.json

@@ -315,12 +315,6 @@
         "title": "Test Tree Grid",
         "parent": ""
     },
-    {
-        "name": "tree_expand_hidden.html",
-        "url": "tree_expand_hidden.html",
-        "title": "Test Tree Grid Expanding while Hidden",
-        "parent": ""
-    },
     {
         "name": "tundra_custom.html",
         "url": "tundra_custom.html",

test/intern/plugins/tree.js

@@ -182,6 +182,22 @@ define([
 					testRowExists("4:99");
 				});
 			});
+
+			test.test("expand hidden", function() {
+				var dfd = this.async(1000);
+
+				grid.domNode.style.display = "none";
+				grid.expand(0);
+				grid.domNode.style.display = "block";
+
+				// Since the grid is not displayed the expansion will occur without a transitionend event
+				// However, DOM updates from the expand will not complete within the current stack frame
+				setTimeout(dfd.callback(function() {
+					var connected = grid.row(0).element.connected;
+					assert.isTrue(connected && connected.offsetHeight > 0,
+						"Node should be expanded with non-zero height");
+				}), 0);
+			});
 		});
 
 		test.suite("tree + observable", function(){
@@ -201,6 +217,5 @@ define([
 				});
 			});
 		});
-
 	});
 });