DevTools: add console test helpers to new test runner & migrate a console test

third_party/WebKit/Source/devtools/front_end/main/errorWarningCounter.css

Index: third_party/WebKit/Source/devtools/front_end/main/errorWarningCounter.css
diff --git a/third_party/WebKit/Source/devtools/front_end/main/errorWarningCounter.css b/third_party/WebKit/Source/devtools/front_end/main/errorWarningCounter.css
deleted file mode 100644
index d6ad447d8fea7fb8f5602628b16d0b0a6a4eaddc..0000000000000000000000000000000000000000
--- a/third_party/WebKit/Source/devtools/front_end/main/errorWarningCounter.css
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
- * Copyright (c) 2015 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.
- */
-
-:host {
-    cursor: pointer;
-    padding: 0 2px;
-    min-width: 26px;
-}
-
-:host:hover {
-    color: #333;
-}
-
-.counter-item {
-    margin-left: 6px;
-}
-
-.counter-item label {
-    cursor: inherit;
-}
-
-.counter-item.counter-item-first {
-    margin-left: 0;
-}