Move backgroundColorOf/backgroundColorShouldBe to shadow-dom.js

LayoutTests/fast/dom/shadow/host-pseudo-class.html

Index: LayoutTests/fast/dom/shadow/host-pseudo-class.html
diff --git a/LayoutTests/fast/dom/shadow/host-pseudo-class.html b/LayoutTests/fast/dom/shadow/host-pseudo-class.html
index 469fda60a113b61c2399cdf5d4c3d19c37c5d6f2..9a8541d60765e825dd25b8330bc5704c4ef600d0 100644
--- a/LayoutTests/fast/dom/shadow/host-pseudo-class.html
+++ b/LayoutTests/fast/dom/shadow/host-pseudo-class.html
@@ -16,14 +16,6 @@ description('Test whether :host matches a shadow host correctly.');
 
 var sandbox = document.getElementById('sandbox');
 
-function backgroundColorOf(selector) {
-    return window.getComputedStyle(getNodeInTreeOfTrees(selector)).backgroundColor;
-}
-
-function backgroundColorShouldBe(selector, expected) {
-    shouldBeEqualToString('backgroundColorOf(\'' + selector + '\')', expected);
-}
-
 function cleanUp() {
     sandbox.innerHTML = '';
 }