Don't move uneditable paragraph contents in CompositeEditCommand::moveParagraphContentsToNewBlockIfN

Source/core/editing/CompositeEditCommand.cpp

Index: Source/core/editing/CompositeEditCommand.cpp
diff --git a/Source/core/editing/CompositeEditCommand.cpp b/Source/core/editing/CompositeEditCommand.cpp
index be168e68a7bbb4d6b062fa2c284353ea24f2a164..8287e455d1d2bac0a9fb01087ea338013e966591 100644
--- a/Source/core/editing/CompositeEditCommand.cpp
+++ b/Source/core/editing/CompositeEditCommand.cpp
@@ -897,10 +897,7 @@ PassRefPtrWillBeRawPtr<Element> CompositeEditCommand::insertNewDefaultParagraphE
 // it, and return that block.  Otherwise return 0.
 PassRefPtrWillBeRawPtr<Element> CompositeEditCommand::moveParagraphContentsToNewBlockIfNecessary(const Position& pos)
 {
-    if (pos.isNull())
-        return nullptr;
-
-    document().updateLayoutIgnorePendingStylesheets();
+    ASSERT(isEditablePosition(pos, ContentIsEditable, DoNotUpdateStyle));
 
     // It's strange that this function is responsible for verifying that pos has not been invalidated
     // by an earlier call to this function.  The caller, applyBlockStyle, should do this.