fix($parse): reduce false-positives in isElement tests

There are always going to be false positives here, unfortunately. But
testing different properties will hopefully reduce the number of false
positives in a meaningful way, without harming performance too much.

Closes angular#4805

Author: caitp

src/ng/parse.js

@@ -55,7 +55,7 @@ function ensureSafeObject(obj, fullExpression) {
           'Referencing the Window in Angular expressions is disallowed! Expression: {0}',
           fullExpression);
     } else if (// isElement(obj)
-        obj.children && (obj.nodeName || (obj.on && obj.find))) {
+        obj.children && (obj.nodeName || (obj.prop && obj.attr && obj.find))) {
       throw $parseMinErr('isecdom',
           'Referencing DOM nodes in Angular expressions is disallowed! Expression: {0}',
           fullExpression);

test/ng/parseSpec.js

@@ -784,6 +784,28 @@ describe('parser', function() {
                       '$parse', 'isecdom', 'Referencing DOM nodes in Angular expressions is ' +
                       'disallowed! Expression: a.b.doc.on("click")');
             }));
+
+            // Issue #4805
+            it('should NOT throw isecdom when referencing a Backbone Collection', function() {
+              // Backbone stuff is sort of hard to mock, if you have a better way of doing this,
+              // please fix this.
+              var fakeBackboneCollection = {
+                children: [{}, {}, {}],
+                find: function() {},
+                on: function() {},
+                off: function() {},
+                bind: function() {}
+              };
+              scope.backbone = fakeBackboneCollection;
+              expect(function() { scope.$eval('backbone'); }).not.toThrow();
+            });
+
+            it('should NOT throw isecdom when referencing an array with node properties', function() {
+              var array = [1,2,3];
+              array.on = array.attr = array.prop = array.bind = true;
+              scope.array = array;
+              expect(function() { scope.$eval('array'); }).not.toThrow();
+            });
           });
         });