Restore HeightPercent for Slider

Change-Id: Iefc8b15e7064d8f460865a77aca2bcdbcf244f65

appinventor/components/src/com/google/appinventor/components/runtime/Slider.java

@@ -468,9 +468,4 @@ public class Slider extends AndroidViewComponent implements SeekBar.OnSeekBarCha
     //ability to change the slider height and don't want display this in our block editor
     container.setChildHeight(this, height);
   }
-
-  @Override
-  public void HeightPercent(int pCent) {
-  }
-
 }

appinventor/docs/html/reference/components/userinterface.html

@@ -1037,6 +1037,9 @@ having dark grey components.</li>
   <dd>Specifies the color of the slider bar to the right of the thumb as an alpha-red-green-blue
  integer, i.e., <code class="highlighter-rouge">0xAARRGGBB</code>.  An alpha of <code class="highlighter-rouge">00</code>
  indicates fully transparent and <code class="highlighter-rouge">FF</code> means opaque.</dd>
+  <dt id="Slider.HeightPercent" class="number wo bo"><em>HeightPercent</em></dt>
+  <dd>Specifies the <code class="highlighter-rouge">Slider</code>’s vertical height as a percentage
+ of the <a href="userinterface.html#Screen.Height"><code class="highlighter-rouge">Screen</code>’s <code class="highlighter-rouge">Height</code></a>.</dd>
   <dt id="Slider.MaxValue" class="number"><em>MaxValue</em></dt>
   <dd>Sets the maximum value of slider. If the new maximum is less than the
  current minimum, then minimum and maximum will both be set to this value.

appinventor/docs/markdown/reference/components/userinterface.md

@@ -1135,6 +1135,10 @@ This class is used to display a `Slider`.
  integer, i.e., `0xAARRGGBB`.  An alpha of `00`
  indicates fully transparent and `FF` means opaque.
 
+{:id="Slider.HeightPercent" .number .wo .bo} *HeightPercent*
+: Specifies the `Slider`'s vertical height as a percentage
+ of the [`Screen`'s `Height`](userinterface.html#Screen.Height).
+
 {:id="Slider.MaxValue" .number} *MaxValue*
 : Sets the maximum value of slider. If the new maximum is less than the
  current minimum, then minimum and maximum will both be set to this value.