Move backgroundColorOf/backgroundColorShouldBe to shadow-dom.js

LayoutTests/fast/dom/shadow/resources/shadow-dom.js

 function createShadowRoot()
 {
     var children = Array.prototype.slice.call(arguments);
     if ((children[0] instanceof Object) && !(children[0] instanceof Node)) {
         var attributes = {};
         var parameter = {};
         for (var key in children[0]) {
             if (key == 'mode' || key == 'delegatesFocus')
                 parameter[key] = children[0][key];
             else
@@ skipping 257 matching lines @@
 
     debug('Traverse in forward.');
     showComposedShadowTreeByTraversingInForward(node);
 
     debug('Traverse in backward.');
     showComposedShadowTreeByTraversingInBackward(node);
 
     debug('');
 }
 
-function showNextNode(node) {
+function showNextNode(node)
+{
     var next = internals.nextInComposedTree(node);
     debug('Next node of [' + dumpNode(node) + '] is [' + dumpNode(next) + ']');
 }
+
+function backgroundColorOf(selector)
+{
+    return window.getComputedStyle(getNodeInTreeOfTrees(selector)).backgroundColor;
+}
+
+function backgroundColorShouldBe(selector, expected)
+{
+    shouldBeEqualToString('backgroundColorOf(\'' + selector + '\')', expected);
+}
+
+function backgroundColorShouldNotBe(selector, color)
+{
+    var text = 'backgroundColorOf(\'' + selector + '\')';
+    var unevaledString = '"' + color.replace(/\\/g, "\\\\").replace(/"/g, "\"") + '"';
+    shouldNotBe(text, unevaledString);
+}