Remove the duplicate Button::pressed property

Make it possible for Button to redefine BasicButton's "effective
pressed" state instead of overshadowing the pressed property.

Task-number: QTBUG-33124
Change-Id: I5b3570c51e1b2f8771f713e8f3f6982757d05770
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Reviewed-by: Caroline Chao <caroline.chao@digia.com>

src/controls/Button.qml

@@ -78,10 +78,7 @@ BasicButton {
      */
     property Menu menu: null
 
-    /*! \qmlproperty bool BasicButton::pressed
-
-        This property holds whether the button is being pressed. */
-    readonly property bool pressed: __behavior.effectivePressed || menu && menu.__popupVisible
+    __effectivePressed: __behavior.effectivePressed || menu && menu.__popupVisible
 
     activeFocusOnTab: true
 

src/controls/Private/BasicButton.qml

@@ -59,7 +59,7 @@ Control {
     /*! \qmlproperty bool BasicButton::pressed
 
         This property holds whether the button is being pressed. */
-    readonly property alias pressed: behavior.effectivePressed
+    readonly property alias pressed: button.__effectivePressed
 
     /*! \qmlproperty bool BasicButton::hovered
 
@@ -202,6 +202,9 @@ Control {
     /*! \internal */
     property var __behavior: behavior
 
+    /*! \internal */
+    property bool __effectivePressed: behavior.effectivePressed
+
     SystemPalette { id: syspal }
 
     states: [