fix for infinite loop in retrieveScope with jQuery + specs

- retrieveScope run into infinite loop if called on DOM tree
  that doesn't contain scope reference (happens only with jQuery)
- added missing specs for retrieveScope function

src/Compiler.js

@@ -75,7 +75,7 @@ Template.prototype = {
 function retrieveScope(element) {
   var scope;
   element = jqLite(element);
-  while (element && !(scope = element.data($$scope))) {
+  while (element && element.length && !(scope = element.data($$scope))) {
     element = element.parent();
   }
   return scope;

test/CompilerSpec.js

@@ -167,4 +167,23 @@ describe('compiler', function(){
     expect(sortedHtml(scope.$element)).toEqual('<div>A<hr></hr>B<hr></hr>C<p></p>D</div>');
   });
 
+
+  describe('retrieveScope', function() {
+    it('should retrieve scope attached to the current element', function() {
+      scope = compile('<i>foo</i>');
+      expect(retrieveScope(scope.$element)).toBe(scope);
+    });
+
+    it('should walk up the dom to find scope', function() {
+      scope = compile('<ul><li><p><b>deep deep</b><p></li></ul>');
+      var deepChild = scope.$element[0].getElementsByTagName('b')[0];
+      expect(retrieveScope(deepChild)).toBe(scope);
+    });
+
+    it('should return undefined when no scope was found', function() {
+      var html = jqLite('<ul><li><p><b>deep deep</b><p></li></ul>'),
+          deepChild = html[0].getElementsByTagName('b')[0];
+      expect(retrieveScope(deepChild)).toBeNull();
+    });
+  });
 });