Restructure pkg/unittest and pkg/webdriver to follow the pub conventions.

tests/html/svg_1_test.dart

-#library('SVG1Test');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
+library SVG1Test;
+import '../../pkg/unittest/lib/unittest.dart';
+import '../../pkg/unittest/lib/html_config.dart';
+import 'dart:html';
 
 // Test that SVG is present in dart:html API
 
 main() {
   useHtmlConfiguration();
 
   var isSVGElement = predicate((x) => x is SVGElement, 'is a SVGElement');
 
   test('simpleRect', () {
       var div = new Element.tag('div');
@@ skipping 21 matching lines @@
     var logo = new SVGElement.svg("""
       <svg xmlns="http://www.w3.org/2000/svg" version="1.1">
         <path/>
       </svg>
       """);
 
   expect(logo, isSVGElement);
 
   });
 }