Fix null dereference on MemoryCache.

third_party/WebKit/Source/core/fetch/StyleSheetResource.h

Index: third_party/WebKit/Source/core/fetch/StyleSheetResource.h
diff --git a/third_party/WebKit/Source/core/fetch/StyleSheetResource.h b/third_party/WebKit/Source/core/fetch/StyleSheetResource.h
index 0b9fb40588fc7b1ef98ee388ddd2a9c11c0d0033..51c8567cbc5e800ab77edcae790ea8535d8c3019 100644
--- a/third_party/WebKit/Source/core/fetch/StyleSheetResource.h
+++ b/third_party/WebKit/Source/core/fetch/StyleSheetResource.h
@@ -31,13 +31,14 @@
 #ifndef StyleSheetResource_h
 #define StyleSheetResource_h
 
+#include "core/CoreExport.h"
 #include "core/fetch/TextResource.h"
 
 namespace blink {
 
 class StyleSheetResourceClient;
 
-class StyleSheetResource : public TextResource {
+class CORE_EXPORT StyleSheetResource : public TextResource {
 public:
     using ClientType = StyleSheetResourceClient;