Bug 1423097 - part 3: Fix new orange caused by an existing bug of EditorBase::DeleteSelectionAndCreateElement() r=m_kato

Even after EditorBase::DeleteSelectionAndCreateElement() creates a new element,
it tries to collapse selection with |pointToInsert| which is outdated after
inserting new element.

So, it should recompute the caret position with new DOM tree.

MozReview-Commit-ID: DKh2uhItIol

--HG--
extra : rebase_source : c0c30e1c809784af64e87596b471c472350857a8

editor/libeditor/EditorBase.cpp

@@ -4490,11 +4490,13 @@ EditorBase::DeleteSelectionAndCreateElement(nsAtom& aTag)
   RefPtr<Element> newElement = CreateNode(&aTag, pointToInsert);
 
   // We want the selection to be just after the new node
-  DebugOnly<bool> advanced = pointToInsert.AdvanceOffset();
+  EditorRawDOMPoint afterNewElement(newElement);
+  MOZ_ASSERT(afterNewElement.IsSetAndValid());
+  DebugOnly<bool> advanced = afterNewElement.AdvanceOffset();
   NS_WARNING_ASSERTION(advanced,
                        "Failed to move offset next to the new element");
   ErrorResult error;
-  selection->Collapse(pointToInsert, error);
+  selection->Collapse(afterNewElement, error);
   if (NS_WARN_IF(error.Failed())) {
     // XXX Even if it succeeded to create new element, this returns error
     //     when Selection.Collapse() fails something.  This could occur with