Allowing font size to properly inherit (#1695)

Fixes #1638

Author: Keboo

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.PasswordBox.xaml

@@ -19,7 +19,6 @@
         <Setter Property="BorderBrush" Value="{DynamicResource MaterialDesignTextBoxBorder}" />
         <Setter Property="PasswordChar" Value="●"/>
         <Setter Property="BorderThickness" Value="0 0 0 1"/>
-        <Setter Property="FontSize" Value="16"/>
         <Setter Property="wpf:TextFieldAssist.TextBoxViewMargin" Value="1 0 0 0" />
         <Setter Property="Background" Value="Transparent"/>
         <Setter Property="CaretBrush" Value="{DynamicResource PrimaryHueMidBrush}" />

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.TextBox.xaml

@@ -18,7 +18,6 @@
         <Setter Property="Foreground" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type FrameworkElement}}, Path=(TextElement.Foreground)}"/>
         <Setter Property="BorderBrush" Value="{DynamicResource MaterialDesignTextBoxBorder}" />
         <Setter Property="BorderThickness" Value="0 0 0 1"/>
-        <Setter Property="FontSize" Value="16"/>
         <Setter Property="wpf:TextFieldAssist.TextBoxViewMargin" Value="1 0 1 0" />
         <Setter Property="Background" Value="Transparent"/>
         <Setter Property="CaretBrush" Value="{DynamicResource PrimaryHueMidBrush}" />