Introduce firstRangeOf() as replacement of VisibleSelection::firstRange()

Source/core/editing/VisibleSelection.h

Index: Source/core/editing/VisibleSelection.h
diff --git a/Source/core/editing/VisibleSelection.h b/Source/core/editing/VisibleSelection.h
index 517023a64911d64670d2cbc36ad3e53117950f69..267368e1ec5cdeb0717589b860ced3b108395c9b 100644
--- a/Source/core/editing/VisibleSelection.h
+++ b/Source/core/editing/VisibleSelection.h
@@ -152,9 +152,6 @@ public:
     bool expandUsingGranularity(TextGranularity);
     bool expandUsingGranularityInComposedTree(TextGranularity);
 
-    // We don't yet support multi-range selections, so we only ever have one range to return.
-    PassRefPtrWillBeRawPtr<Range> firstRange() const;
-
     bool intersectsNode(Node*) const;
 
     // FIXME: Most callers probably don't want these functions, but
@@ -257,6 +254,10 @@ private:
     bool m_isDirectional : 1; // Non-directional ignores m_baseIsFirst and selection always extends on shift + arrow key.
 };
 
+// We don't yet support multi-range selections, so we only ever have one range
+// to return.
+CORE_EXPORT PassRefPtrWillBeRawPtr<Range> firstRangeOf(const VisibleSelection&);
+
 } // namespace blink
 
 #ifndef NDEBUG