Add SpellCheckMarkerList in preparation for DocumentMarkerController refactor

third_party/WebKit/Source/core/editing/BUILD.gn

Index: third_party/WebKit/Source/core/editing/BUILD.gn
diff --git a/third_party/WebKit/Source/core/editing/BUILD.gn b/third_party/WebKit/Source/core/editing/BUILD.gn
index aae986e44acde16d9a1ea460d295f9b26ef7a104..722732593143b85df8049486a5aba4a23c7cd227 100644
--- a/third_party/WebKit/Source/core/editing/BUILD.gn
+++ b/third_party/WebKit/Source/core/editing/BUILD.gn
@@ -197,6 +197,8 @@ blink_core_sources("editing") {
     "markers/EditingMarkerList.cpp",
     "markers/EditingMarkerList.h",
     "markers/RenderedDocumentMarker.h",
+    "markers/SpellCheckMarkerList.cpp",
+    "markers/SpellCheckMarkerList.h",
     "serializers/HTMLInterchange.cpp",
     "serializers/HTMLInterchange.h",
     "serializers/MarkupAccumulator.cpp",
@@ -293,6 +295,7 @@ source_set("unit_tests") {
     "markers/DocumentMarkerListTest.cpp",
     "markers/DocumentMarkerTest.cpp",
     "markers/EditingMarkerListTest.cpp",
+    "markers/SpellCheckMarkerListTest.cpp",
     "serializers/StyledMarkupSerializerTest.cpp",
     "spellcheck/IdleSpellCheckCallbackTest.cpp",
     "spellcheck/SpellCheckTestBase.cpp",