[Tree] Don't assume context capability is present

Addresses #753 (newly-created objects may not have context,
causing errors when these are encountered by TreeNodeView)

platform/commonUI/general/src/ui/TreeNodeView.js

@@ -81,13 +81,13 @@ define([
     };
 
     function getIdPath(domainObject) {
+        var context = domainObject && domainObject.getCapability('context');
+
         function getId(domainObject) {
             return domainObject.getId();
         }
 
-        return domainObject ?
+        return context ? context.getPath().map(getId) : [];
-            domainObject.getCapability('context').getPath().map(getId) :
-            [];
     }
 
     TreeNodeView.prototype.value = function (domainObject) {

platform/commonUI/general/test/ui/TreeViewSpec.js

@@ -200,6 +200,21 @@ define([
                 });
             });
 
+            describe("when a context-less object is selected", function () {
+                beforeEach(function () {
+                    var testCapabilities = makeGenericCapabilities(),
+                        mockDomainObject =
+                            makeMockDomainObject('xyz', {}, testCapabilities);
+                    delete testCapabilities.context;
+                    treeView.value(mockDomainObject);
+                });
+
+                it("clears all selection state", function () {
+                    var selected = $(treeView.elements()[0]).find('.selected');
+                    expect(selected.length).toEqual(0);
+                });
+            });
+
             describe("when children contain children", function () {
                 beforeEach(function () {
                     var newCapabilities = makeGenericCapabilities(),