Componentization: make core/dom visible for blink_web and blink_tests.

Source/core/dom/custom/CustomElementProcessingStack.h

Index: Source/core/dom/custom/CustomElementProcessingStack.h
diff --git a/Source/core/dom/custom/CustomElementProcessingStack.h b/Source/core/dom/custom/CustomElementProcessingStack.h
index 742d3d536b83e398bead9933f00c2f4a27210c6e..a6aaf11b84731d558f5fc2b379dd46bd0457b0ad 100644
--- a/Source/core/dom/custom/CustomElementProcessingStack.h
+++ b/Source/core/dom/custom/CustomElementProcessingStack.h
@@ -31,12 +31,13 @@
 #ifndef CustomElementProcessingStack_h
 #define CustomElementProcessingStack_h
 
+#include "core/CoreExport.h"
 #include "core/dom/custom/CustomElementCallbackQueue.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
-class CustomElementProcessingStack {
+class CORE_EXPORT CustomElementProcessingStack {
     WTF_MAKE_NONCOPYABLE(CustomElementProcessingStack);
 public:
     // This is stack allocated in many DOM callbacks. Make it cheap.