Avoid triggering indent for electric characters in comments and strings

In comments and strings, electric characters have no syntactical
significance and the unnecessary automatic reindent can be annoying.

Reviewed-by: Erik Verbruggen

src/plugins/texteditor/basetexteditor.h

@@ -403,6 +403,7 @@ protected:
     virtual void reindent(QTextDocument *doc, const QTextCursor &cursor);
 
     virtual bool contextAllowsAutoParentheses(const QTextCursor &cursor, const QString &textToInsert = QString()) const;
+    virtual bool contextAllowsElectricCharacters(const QTextCursor &cursor) const;
 
     // Returns true if the cursor is inside a comment.
     virtual bool isInComment(const QTextCursor &cursor) const;