Use lineedit svg margins in sizeHint calculation

QQC button heights are max(backgroundHeight, label + margins).
QQC lineedits are only from the background

We need to take the margins into consideration when deciding how high
the textbox should be otherwise we're effectively just ignoring what the
SVG says.

This means button and textbox on the login screen are now the same
height.

REVIEW: 125240

src/declarativeimports/plasmastyle/TextFieldStyle.qml

@@ -42,7 +42,13 @@ QtQuickControlStyle.TextFieldStyle {
     renderType: control.echoMode == TextInput.Normal ? Text.NativeRendering : Text.QtRendering
 
     background: Item {
-        implicitHeight: theme.mSize(theme.defaultFont).height * 1.6
+        //QQC button heights are max(backgroundHeight, label + margins).
+        //QQC lineedits are only from the background (and if background is not set, just an arbirtary value of 25)
+        //Why? I don't know
+
+        //In order to get the same height in both buttons and lineedits we need to apply the same rule here
+
+        implicitHeight: Math.max(theme.mSize(theme.defaultFont).height * 1.6, theme.mSize(theme.defaultFont).height + base.margins.top + base.margins.bottom)
         implicitWidth: theme.mSize(theme.defaultFont).width * 12
 
         Private.TextFieldFocus {
@@ -53,8 +59,6 @@ QtQuickControlStyle.TextFieldStyle {
         PlasmaCore.FrameSvgItem {
             id: base
             anchors.fill: parent
-            // TODO: see what is the correct policy for margins
-            //anchors.fill: parent
             imagePath: "widgets/lineedit"
             prefix: "base"
         }

tests/components/button.qml

@@ -2,6 +2,7 @@ import QtQuick 2.0
 
 import org.kde.plasma.components 2.0 as PlasmaComponents
 import QtQuick.Controls 1.2
+import QtQuick.Layouts 1.2
 
 Rectangle
 {
@@ -93,6 +94,19 @@ Rectangle
                     }
             }
         }
+
+        Label {
+            text: "button and textfield should have the same height"
+        }
+
+        RowLayout {
+            PlasmaComponents.Button {
+                text: "test"
+            }
+            PlasmaComponents.TextField {
+            }
+        }
+
     }
 }