Don't duplicate background resizing to contents

The code in Button is
panel.implicitWidth: max(label+borders, backgroundImplicitSize)

by setting the background implicitSize to be max(size, labels+borders)
we just duplicate the functionality.

This worked, but icon only buttons became smaller because we weren't
setting the implicitHeight of the label properly.

(two wrongs were making a right)

We need to move the RowLayout inside an Item as we are modiyfing the
preferredHeight of RowLayout, but this doesn't sync back to updating the
implicitHeight which Button.qml uses.

This fixes all binding loops and the rather broken icon only flat
button.

Change-Id: Id2f9c2ab37b2280ee69dc1473f388fe686e3327e

src/declarativeimports/plasmacomponents/qml/styles/ToolButtonStyle.qml

@@ -34,9 +34,16 @@ QtQuickControlStyle.ButtonStyle {
     property int minimumWidth
     property int minimumHeight
 
-    label: RowLayout {
+    label: Item {
+        //wrapper is needed as we are adjusting the preferredHeight of the layout from the default
+        //and the implicitHeight is implicitly read only
+        implicitHeight: buttonContent.Layout.preferredHeight
+        implicitWidth: buttonContent.implicitWidth
+        RowLayout {
             id: buttonContent
+            anchors.fill: parent
             spacing: units.smallSpacing
+
             Layout.preferredHeight: Math.max(units.iconSizes.small, label.implicitHeight)
 
             property real minimumWidth: Layout.minimumWidth + style.padding.left + style.padding.right
@@ -59,6 +66,10 @@ QtQuickControlStyle.ButtonStyle {
                 id: icon
                 source: control.iconName || control.iconSource
                 anchors.verticalCenter: parent.verticalCenter
+
+                implicitHeight: label.implicitHeight
+                implicitWidth: implicitHeight
+
                 Layout.minimumWidth: valid ? parent.height: 0
                 Layout.maximumWidth: Layout.minimumWidth
                 visible: valid
@@ -104,6 +115,7 @@ QtQuickControlStyle.ButtonStyle {
                 }
             }
         }
+    }
 
     background: {
         if (control.text.length == 0 && control.width == control.height && (control.parent && control.parent.checkedButton === undefined) && !control.flat) {
@@ -117,7 +129,9 @@ QtQuickControlStyle.ButtonStyle {
         id: roundButtonComponent
         Item {
             id: roundButtonDelegate
-            anchors.fill: parent
+            implicitHeight: Math.floor(theme.mSize(theme.defaultFont).height*1.6)
+            implicitWidth: implicitHeight
+
             property QtObject margins: QtObject {
                 property int left: control.width/8
                 property int top: control.width/8
@@ -166,13 +180,13 @@ QtQuickControlStyle.ButtonStyle {
         id: buttonComponent
         Item {
             id: buttonSurface
-            implicitHeight: Math.floor(Math.max(theme.mSize(theme.defaultFont).height*1.6, style.minimumHeight))
+            implicitHeight: Math.floor(theme.mSize(theme.defaultFont).height*1.6)
 
             implicitWidth: {
                 if (control.text.length == 0) {
                     implicitHeight;
                 } else {
-                    Math.max(theme.mSize(theme.defaultFont).width*12, style.minimumWidth);
+                    Math.floor(theme.mSize(theme.defaultFont).width*12);
                 }
             }
             Connections {