Export TaskRunnerHelper functions to expose it to modules/

third_party/WebKit/Source/core/dom/TaskRunnerHelper.h

Index: third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
diff --git a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
index be7fc40006be54c20e0d6a154d1bd5c2ec7ce34c..19a0983c82539672a0586d69189df381806c98a5 100644
--- a/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
+++ b/third_party/WebKit/Source/core/dom/TaskRunnerHelper.h
@@ -5,6 +5,7 @@
 #ifndef TaskRunnerHelper_h
 #define TaskRunnerHelper_h
 
+#include "core/CoreExport.h"
 #include "wtf/Allocator.h"
 
 namespace blink {
@@ -15,7 +16,7 @@ class LocalFrame;
 class ScriptState;
 class WebTaskRunner;
 
-class TaskRunnerHelper final {
+class CORE_EXPORT TaskRunnerHelper final {
     STATIC_ONLY(TaskRunnerHelper);
 public:
     static WebTaskRunner* getUnthrottledTaskRunner(LocalFrame*);