Don't indent if selection is none.

Source/core/editing/ApplyBlockElementCommand.cpp

Index: Source/core/editing/ApplyBlockElementCommand.cpp
diff --git a/Source/core/editing/ApplyBlockElementCommand.cpp b/Source/core/editing/ApplyBlockElementCommand.cpp
index 5ecf67a627649d9769d1236f31b5f777fb76fb77..8467d47eb5034aceaf460169541d880aab429945 100644
--- a/Source/core/editing/ApplyBlockElementCommand.cpp
+++ b/Source/core/editing/ApplyBlockElementCommand.cpp
@@ -73,8 +73,12 @@ void ApplyBlockElementCommand::doApply()
     // FIXME: We paint the gap before some paragraphs that are indented with left
     // margin/padding, but not others.  We should make the gap painting more consistent and
     // then use a left margin/padding rule here.
-    if (visibleEnd != visibleStart && isStartOfParagraph(visibleEnd))
-        setEndingSelection(VisibleSelection(visibleStart, visibleEnd.previous(CannotCrossEditingBoundary), endingSelection().isDirectional()));
+    if (visibleEnd != visibleStart && isStartOfParagraph(visibleEnd)) {
+        VisibleSelection newSelection(visibleStart, visibleEnd.previous(CannotCrossEditingBoundary), endingSelection().isDirectional());
+        if (newSelection.isNone())
+            return;
+        setEndingSelection(newSelection);
+    }
 
     VisibleSelection selection = selectionForParagraphIteration(endingSelection());
     VisiblePosition startOfSelection = selection.visibleStart();