Don't save matrix when using canvas.save

Summary:
Canvas.save by default saves both the matrix (for translations,
scaling, etc) and the clip (clipRect) - in most of our cases, we really only
care to save and restore the clip, not the matrix.

Reviewed By: sriramramani

Differential Revision: D3235698

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

@@ -31,7 +31,7 @@ import android.graphics.Canvas;
   public final void draw(FlatViewGroup parent, Canvas canvas) {
     onPreDraw(parent, canvas);
     if (shouldClip()) {
-      canvas.save();
+      canvas.save(Canvas.CLIP_SAVE_FLAG);
       applyClipping(canvas);
       onDraw(canvas);
       canvas.restore();