Port pixelzoomer.js/css to ct-results-comparison.

Tools/GardeningServer/ui/ct-results-comparison-zoomer-tests.html

+<!--
+Copyright 2014 The Chromium Authors. All rights reserved.
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file.
+-->
+
+<link rel="import" href="ct-results-comparison-zoomer.html">
+
+<script>
+(function () {
+
+module("ct-results-comparison-zoomer");
+
+asyncTest("no-position", 2, function() {
+  var zoomer = document.createElement('ct-results-comparison-zoomer');
+  // FIXME: This should set zoomer.position instead, but there's no way
+  // to get between the microtask and requestAnimationFrame to verify the
+  // behavior.
+  zoomer.positionChanged();
+  ok(zoomer._drawScheduled);
+
+  requestAnimationFrame(function() {
+    ok(!zoomer._drawScheduled);
+    start();
+  });
+});
+
+test("draw", 3, function() {
+  // Hard to verify correct behavior here, but at least make sure the
+  // code executes without throwing errors.
+
+  var zoomer = document.createElement('ct-results-comparison-zoomer');
+
+  try {
+    zoomer._drawAll();
+    ok(true);
+  } catch(e) {
+    ok(false);
+  }
+
+  // FIXME: Use a proper model class instead of a dumb object.
+  zoomer.position = {x: 0, y: 0};
+  try {
+    zoomer._drawAll();
+    ok(true);
+  } catch(e) {
+    ok(false);
+  }
+
+  try {
+    zoomer._draw(zoomer.$.diffZoomer);
+    ok(true);
+  } catch(e) {
+    ok(false);
+  }
+});
+
+})()
+</script>