Fix measure of ReactSlider for Android API < 21

Summary:
This diff avoids calling to the method setStateListAnimator for users running in Android API < 21 (This method did not exist in Android API < 21)

changelog: [Android][Fix] Fix crash while measuring ReactSlider in Android API < 21

Reviewed By: lunaleaps

Differential Revision: D22164574

fbshipit-source-id: 8163f99eeb78302fc75e2c4938330c699ca8d363

ReactAndroid/src/main/java/com/facebook/react/views/slider/ReactSlider.java

@@ -53,7 +53,7 @@ public ReactSlider(Context context, @Nullable AttributeSet attrs, int style) {
     disableStateListAnimatorIfNeeded();
   }
 
-  private void disableStateListAnimatorIfNeeded() {
+  /* package */ void disableStateListAnimatorIfNeeded() {
     // We disable the state list animator for Android 6 and 7; this is a hack to prevent T37452851
     // and https://github.com/facebook/react-native/issues/9979
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M

ReactAndroid/src/main/java/com/facebook/react/views/slider/ReactSliderManager.java

@@ -72,11 +72,11 @@ public long measure(
         float height,
         YogaMeasureMode heightMode) {
       if (!mMeasured) {
-        SeekBar reactSlider = new ReactSlider(getThemedContext(), null, STYLE);
+        ReactSlider reactSlider = new ReactSlider(getThemedContext(), null, STYLE);
         // reactSlider is used for measurements purposes, it is not necessary to set a
         // StateListAnimator.
         // It is not safe to access StateListAnimator from a background thread.
-        reactSlider.setStateListAnimator(null);
+        reactSlider.disableStateListAnimatorIfNeeded();
         final int spec =
             View.MeasureSpec.makeMeasureSpec(
                 ViewGroup.LayoutParams.WRAP_CONTENT, View.MeasureSpec.UNSPECIFIED);