[DMC #21] Add check to make TextMatchMarker cast safer

third_party/WebKit/Source/core/editing/markers/TextMatchMarker.h

Index: third_party/WebKit/Source/core/editing/markers/TextMatchMarker.h
diff --git a/third_party/WebKit/Source/core/editing/markers/TextMatchMarker.h b/third_party/WebKit/Source/core/editing/markers/TextMatchMarker.h
index b7025f55875c58fbd3e84aa20bf0c5eff44d21aa..f5501f5e834da0964a31e05f0784fecab4926aee 100644
--- a/third_party/WebKit/Source/core/editing/markers/TextMatchMarker.h
+++ b/third_party/WebKit/Source/core/editing/markers/TextMatchMarker.h
@@ -75,7 +75,11 @@ class TextMatchMarker final : public DocumentMarker {
   State state_;
 };
 
-DEFINE_TYPE_CASTS(TextMatchMarker, DocumentMarker, marker, true, true);
+DEFINE_TYPE_CASTS(TextMatchMarker,
+                  DocumentMarker,
+                  marker,
+                  marker->GetType() == DocumentMarker::kTextMatch,
+                  marker.GetType() == DocumentMarker::kTextMatch);
 
 }  // namespace blink