Add CORE_EXPORRT to ConvertToSelectionInDOMTree() and ConvertToSelectionInFlatTree().

This patch wilk add CORE_EXPORT to convertToSelectionInDOMTree() and
ConvertToSelectionInFlatTree() in SelectionTemplate.h, to utilize these
methods for selection conversion between a flat tree and a dom tree.
This patch is for the SelectionModifier on flat tree changes.

Change-Id: Id847872a6699448e4db3b852c96ae2edb7a68306
Reviewed-on: https://chromium-review.googlesource.com/690134Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Akari Asai <akariasai@google.com>
Cr-Commit-Position: refs/heads/master@{#505240}

third_party/WebKit/Source/core/editing/SelectionTemplate.h

@@ -160,8 +160,10 @@ extern template class CORE_EXTERN_TEMPLATE_EXPORT
 using SelectionInDOMTree = SelectionTemplate<EditingStrategy>;
 using SelectionInFlatTree = SelectionTemplate<EditingInFlatTreeStrategy>;
 
-SelectionInDOMTree ConvertToSelectionInDOMTree(const SelectionInFlatTree&);
-SelectionInFlatTree ConvertToSelectionInFlatTree(const SelectionInDOMTree&);
+CORE_EXPORT SelectionInDOMTree
+ConvertToSelectionInDOMTree(const SelectionInFlatTree&);
+CORE_EXPORT SelectionInFlatTree
+ConvertToSelectionInFlatTree(const SelectionInDOMTree&);
 
 CORE_EXPORT std::ostream& operator<<(std::ostream&, const SelectionInDOMTree&);
 CORE_EXPORT std::ostream& operator<<(std::ostream&, const SelectionInFlatTree&);