Move unittest from lib to pkg.

tests/html/htmlcollection_test.dart

 #library('ElementListTest');
-#import('../../lib/unittest/unittest.dart');
-#import('../../lib/unittest/html_config.dart');
+#import('../../pkg/unittest/unittest.dart');
+#import('../../pkg/unittest/html_config.dart');
 #import('dart:html');
 
 // Test that ElementList implements List<T>
 main() {
   Element insertTestDiv() {
     Element element = new Element.tag('div');
     element.innerHTML = @"""
 <div id='allChecked'>
 <input type="checkbox" name="c1" value="1" checked="yes">
 <input type="checkbox" name="c2" value="2" checked="yes">
@@ skipping 254 matching lines @@
     Expect.equals(-1, someChecked.lastIndexOf(someChecked[3], 2));
 
     Expect.equals(-1, someChecked.lastIndexOf(noneChecked[0], 3));
     Expect.equals(-1, noneChecked.lastIndexOf(someChecked[0], 3));
     Expect.equals(-1, someChecked.lastIndexOf(noneChecked[1], 3));
     Expect.equals(-1, noneChecked.lastIndexOf(someChecked[1], 3));
 
     root.remove();
   });
 }