Have EditCommand classes deal with Document references, not pointers

Source/core/editing/InsertLineBreakCommand.h

Index: Source/core/editing/InsertLineBreakCommand.h
diff --git a/Source/core/editing/InsertLineBreakCommand.h b/Source/core/editing/InsertLineBreakCommand.h
index f1f5d6bce79a15206242414c5d3df6e385f1d39f..6eee0e0d595cc11e78b683f2a0f95ab3fdb62e00 100644
--- a/Source/core/editing/InsertLineBreakCommand.h
+++ b/Source/core/editing/InsertLineBreakCommand.h
@@ -32,13 +32,13 @@ namespace WebCore {
 
 class InsertLineBreakCommand : public CompositeEditCommand {
 public:
-    static PassRefPtr<InsertLineBreakCommand> create(Document* document)
+    static PassRefPtr<InsertLineBreakCommand> create(Document& document)
     {
         return adoptRef(new InsertLineBreakCommand(document));
     }
 
 private:
-    explicit InsertLineBreakCommand(Document*);
+    explicit InsertLineBreakCommand(Document&);
 
     virtual void doApply();