Size height of Android Text component based on includeFontPadding style

Summary:
Overview -

This PR resolves the issue described in #14606. This PR makes Text components take into account the includeFontPadding property when calculating their size.

Background -

Currently, on Android, when includeFontPadding is set to false, the React Text component does not adjust its height. This makes it difficult to lay out other components at a precise spacing relative to a Text component.

iOS calculates the height of a UILabel based on the font's descent + ascent.

Android lets you choose whether to calculate the height of a TextView based on the font's top + bottom (includeFontPadding=true) or ascent + descent (includeFontPadding=false).

In order for a text component to be the same size on iOS and Android (relative to the rest of the layout in points and dips), one should set includeFontPadding=false on Android - but the React Text component needs to take this property into account when sizing itself for this to work.

Please see this stack overflow post for a visual explanation of the difference between a font's ascent/descent and top/bottom - https://stackoverflow.com/questions/27631736/meaning-of-top-ascent-baseline-descent-bottom-and-leading-in-androids-font

Testing -

Please see the attached screenshots to see the height difference of a Text component with this PR when includeFontPadding is true vs false.

The font I am using has an ascent + descent = em-size so that the height of the Text component will be equal to the font-size for a single line of text. This is to clearly show the additional height that includeFontPadding=true adds to the Text component.

For Text components that are styled in the same way,

When includeFontPadding=true, height = ~29.714 dips
When includeFontPadding=false, height= 24 dips

<img width="342" alt="includefontpaddingtrue" src="https://user-images.githubusercontent.com/1437344/27299391-3eec9de0-54fa-11e7-81d5-d0aeb40e8e27.png">

<img width="346" alt="includefontpaddingfalse" src="https://user-images.githubusercontent.com/1437344/27299401-45c95248-54fa-11e7-98d7-17dd152d3cb8.png">
Closes https://github.com/facebook/react-native/pull/14609

Reviewed By: AaaChiuuu

Differential Revision: D5587602

Pulled By: achen1

fbshipit-source-id: 6d2f12ba72ec7462676645519cd27820279278eb

ReactAndroid/src/main/java/com/facebook/react/flat/RCTText.java

@@ -57,6 +57,7 @@ import com.facebook.react.uimanager.annotations.ReactProp;
   private float mSpacingAdd = 0.0f;
   private int mNumberOfLines = Integer.MAX_VALUE;
   private int mAlignment = Gravity.NO_GRAVITY;
+  private boolean mIncludeFontPadding = true;
 
   public RCTText() {
     setMeasureFunction(this);
@@ -94,7 +95,7 @@ import com.facebook.react.uimanager.annotations.ReactProp;
         (int) Math.ceil(width),
         widthMode,
         TextUtils.TruncateAt.END,
-        true,
+        mIncludeFontPadding,
         mNumberOfLines,
         mNumberOfLines == 1,
         text,
@@ -158,7 +159,7 @@ import com.facebook.react.uimanager.annotations.ReactProp;
           (int) Math.ceil(right - left),
           YogaMeasureMode.EXACTLY,
           TextUtils.TruncateAt.END,
-          true,
+          mIncludeFontPadding,
           mNumberOfLines,
           mNumberOfLines == 1,
           mText,
@@ -223,6 +224,11 @@ import com.facebook.react.uimanager.annotations.ReactProp;
     notifyChanged(true);
   }
 
+  @ReactProp(name = ViewProps.INCLUDE_FONT_PADDING, defaultBoolean = true)
+  public void setIncludeFontPadding(boolean includepad) {
+    mIncludeFontPadding = includepad;
+  }
+
   @Override
   /* package */ void updateNodeRegion(
       float left,