Rename Node::lastDescendant() / Node::highestAncestor() for clarity

Source/core/editing/ApplyStyleCommand.cpp

Index: Source/core/editing/ApplyStyleCommand.cpp
diff --git a/Source/core/editing/ApplyStyleCommand.cpp b/Source/core/editing/ApplyStyleCommand.cpp
index 4b1ded9d2abd93d3fe38a8721bc5524e1112961a..c7fbf6a55d339130edd3f5f859d9a6f0515decf6 100644
--- a/Source/core/editing/ApplyStyleCommand.cpp
+++ b/Source/core/editing/ApplyStyleCommand.cpp
@@ -254,7 +254,7 @@ void ApplyStyleCommand::applyBlockStyle(EditingStyle *style)
     // Save and restore the selection endpoints using their indices in the document, since
     // addBlockStyleIfNeeded may moveParagraphs, which can remove these endpoints.
     // Calculate start and end indices from the start of the tree that they're in.
-    Node& scope = visibleStart.deepEquivalent().deprecatedNode()->highestAncestor();
+    Node& scope = visibleStart.deepEquivalent().deprecatedNode()->highestAncestorOrSelf();
     RefPtrWillBeRawPtr<Range> startRange = Range::create(document(), firstPositionInNode(&scope), visibleStart.deepEquivalent().parentAnchoredEquivalent());
     RefPtrWillBeRawPtr<Range> endRange = Range::create(document(), firstPositionInNode(&scope), visibleEnd.deepEquivalent().parentAnchoredEquivalent());
     int startIndex = TextIterator::rangeLength(startRange.get(), true);