Update unittest to new package layout.

tests/html/svg_2_test.dart

 #library('SVG2Test');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
+#import('../../pkg/unittest/lib/unittest.dart');
+#import('../../pkg/unittest/lib/html_config.dart');
 #import('dart:html');
 
 // Test that SVG elements explicitly implement the IDL interfaces (is-checks
 // only, see SVGTest3 for behavioural tests).
 
 main() {
 
   insertTestDiv() {
     var element = new Element.tag('div');
     element.innerHTML = @'''
@@ skipping 25 matching lines @@
       Expect.isTrue(r is SVGLocatable);
 
       // Interfaces not implemented.
       Expect.isFalse(r is SVGNumber);
       Expect.isFalse(r is SVGRect);
       Expect.isFalse(r is SVGSVGElement);
 
       div.remove();
     });
 }