Add default implementation for IDocument::fallbackSaveAs(Path|FileName)

The methods are only relevant for documents without a filePath, and
there was a mix of different irrelevant implementations present in
subclasses.

Change-Id: I4f57d306e5ddd913974cfe6ed0b4db062eb907a1
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

src/plugins/cmakeprojectmanager/cmakeeditor.cpp

@@ -241,9 +241,6 @@ class CMakeDocument : public TextDocument
 {
 public:
     CMakeDocument();
-
-    QString fallbackSaveAsPath() const override;
-    QString fallbackSaveAsFileName() const override;
 };
 
 CMakeDocument::CMakeDocument()
@@ -252,16 +249,6 @@ CMakeDocument::CMakeDocument()
     setMimeType(QLatin1String(Constants::CMAKEMIMETYPE));
 }
 
-QString CMakeDocument::fallbackSaveAsPath() const
-{
-    return filePath().toFileInfo().absolutePath();
-}
-
-QString CMakeDocument::fallbackSaveAsFileName() const
-{
-    return filePath().fileName();
-}
-
 //
 // CMakeEditorFactory
 //