Revert of Fix leaks in exensions_unittests after enabling Oilpan

extensions/renderer/module_system_test.cc

Index: extensions/renderer/module_system_test.cc
diff --git a/extensions/renderer/module_system_test.cc b/extensions/renderer/module_system_test.cc
index 50de79fe954fb4adb62c484aac81fc2e32634df9..68c4bd1fedbea1ba0756956cf5a14423eca2e402 100644
--- a/extensions/renderer/module_system_test.cc
+++ b/extensions/renderer/module_system_test.cc
@@ -22,7 +22,6 @@
 #include "extensions/renderer/object_backed_native_handler.h"
 #include "extensions/renderer/safe_builtins.h"
 #include "extensions/renderer/utils_native_handler.h"
-#include "third_party/WebKit/public/web/WebHeap.h"
 #include "ui/base/resource/resource_bundle.h"
 
 namespace extensions {
@@ -241,7 +240,6 @@ void ModuleSystemTest::TearDown() {
     old_heap_size = stats.used_heap_size();
     isolate_->RequestGarbageCollectionForTesting(
         v8::Isolate::kFullGarbageCollection);
-    blink::WebHeap::collectAllGarbageForTesting();
     isolate_->GetHeapStatistics(&stats);
   }
 }