Layout Tests: Remove stringifyDOMObject() helper

third_party/WebKit/LayoutTests/http/tests/resources/testharness-helpers.js

Index: third_party/WebKit/LayoutTests/http/tests/resources/testharness-helpers.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/resources/testharness-helpers.js b/third_party/WebKit/LayoutTests/http/tests/resources/testharness-helpers.js
index 1d7b8c85b7dca5a4f4532f805731dbc0750ca495..e4885727b321c704dcb434ee9ad7158312735294 100644
--- a/third_party/WebKit/LayoutTests/http/tests/resources/testharness-helpers.js
+++ b/third_party/WebKit/LayoutTests/http/tests/resources/testharness-helpers.js
@@ -31,20 +31,3 @@ function assert_promise_rejects(promise, code, description) {
       }
     });
 }
-
-// Stringifies a DOM object.  This function stringifies not only own properties
-// but also DOM attributes which are on a prototype chain.  Note that
-// JSON.stringify only stringifies own properties.
-function stringifyDOMObject(object)
-{
-    function deepCopy(src) {
-        if (typeof src != "object")
-            return src;
-        var dst = Array.isArray(src) ? [] : {};
-        for (var property in src) {
-            dst[property] = deepCopy(src[property]);
-        }
-        return dst;
-    }
-    return JSON.stringify(deepCopy(object));
-}