QmlJS: Clean up QML console editor

Align the text between editing and display mode, and remove the dead
code. The prompt sign does not have to be part of the text and the
JS parser does not have to retain the code it parses.

Change-Id: I6e41f4fbc2cc863c84677640826d8663bcc648fb
Task-number: QTCREATORBUG-14931
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/qmljstools/qmlconsoleedit.h

@@ -49,7 +49,6 @@ public:
 
 protected:
     void keyPressEvent(QKeyEvent *e);
-    void contextMenuEvent(QContextMenuEvent *event);
     void focusOutEvent(QFocusEvent *e);
 
 signals:
@@ -64,8 +63,6 @@ protected:
 private:
     QModelIndex m_historyIndex;
     QString m_cachedScript;
-    QImage m_prompt;
-    int m_startOfEditableArea;
     QmlJSInterpreter m_interpreter;
 };