Revert "Mark supportsPointConversions deprecated and always true rather than testing DOMPoint"

tests/html/css_test.dart

 library CssTest;
-
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_individual_config.dart';
 import 'dart:html';
 
 main() {
   useHtmlIndividualConfiguration();
 
   group('supportsPointConversions', () {
     test('supported', () {
       expect(Window.supportsPointConversions, true);
     });
   });
 
   group('functional', () {
     test('DomPoint', () {
-      Element element = new Element.tag('div');
-      element.attributes['style'] = '''
+      var expectation = Window.supportsPointConversions ?
+          returnsNormally : throws;
+      expect(() {
+        Element element = new Element.tag('div');
+        element.attributes['style'] =
+          '''
           position: absolute;
           width: 60px;
           height: 100px;
           left: 0px;
           top: 0px;
           background-color: red;
           -webkit-transform: translate3d(250px, 100px, 0px);
           -moz-transform: translate3d(250px, 100px, 0px);
           ''';
-      document.body.append(element);
+        document.body.append(element);
 
-      var elemRect = element.getBoundingClientRect();
+        var elemRect = element.getBoundingClientRect();
 
-      checkPoint(250, 100, new Point(elemRect.left, elemRect.top));
-      checkPoint(310, 200, new Point(elemRect.right, elemRect.bottom));
+        checkPoint(250, 100, new Point(elemRect.left, elemRect.top));
+        checkPoint(310, 200, new Point(elemRect.right, elemRect.bottom));
+      }, expectation);
     });
   });
 }
 
 void checkPoint(expectedX, expectedY, Point point) {
   expect(point.x.round(), equals(expectedX), reason: 'Wrong point.x');
   expect(point.y.round(), equals(expectedY), reason: 'Wrong point.y');
 }