Revert of Implement timers by posting delayed tasks

Source/core/fetch/ResourceTest.cpp

Index: Source/core/fetch/ResourceTest.cpp
diff --git a/Source/core/fetch/ResourceTest.cpp b/Source/core/fetch/ResourceTest.cpp
index 5dd02c66dd8a81713f34f16d74ffa465dc483415..9cd3cf1fa408f0209b66bc06c8075b48fdc32d28 100644
--- a/Source/core/fetch/ResourceTest.cpp
+++ b/Source/core/fetch/ResourceTest.cpp
@@ -22,7 +22,7 @@
 
 class MockPlatform final : public Platform {
 public:
-    MockPlatform() : m_oldPlatform(Platform::current()) { }
+    MockPlatform() { }
     ~MockPlatform() override { }
 
     // From blink::Platform:
@@ -40,13 +40,7 @@
         return m_cachedURLs;
     }
 
-    WebThread* currentThread() override
-    {
-        return m_oldPlatform->currentThread();
-    }
-
 private:
-    Platform* m_oldPlatform; // Not owned.
     Vector<WebURL> m_cachedURLs;
 };