Chunk up the text to spell check also when the text is pasted.

Source/core/editing/TextCheckingHelper.h

Index: Source/core/editing/TextCheckingHelper.h
diff --git a/Source/core/editing/TextCheckingHelper.h b/Source/core/editing/TextCheckingHelper.h
index b67e21797aef8303e4127e5956dd9a3852a2689a..cd1bc09a455b2d1a935ef4edf665c0dbc78344da 100644
--- a/Source/core/editing/TextCheckingHelper.h
+++ b/Source/core/editing/TextCheckingHelper.h
@@ -59,10 +59,10 @@ public:
 
     bool checkingRangeCovers(int location, int length) const { return location < checkingEnd() && location + length > checkingStart(); }
     PassRefPtr<Range> paragraphRange() const;
+    PassRefPtr<Range> checkingRange() const { return m_checkingRange; }
 
 private:
     void invalidateParagraphRangeValues();
-    PassRefPtr<Range> checkingRange() const { return m_checkingRange; }
     PassRefPtr<Range> offsetAsRange() const;
 
     RefPtr<Range> m_checkingRange;