Expose layout diffing flag to java

Summary:
This diff exposes `shouldDiffLayoutWithoutLegacyStretchBehaviour` from YGConfig and `doesLegacyStretchFlagAffectsLayout` from YGLayout to YogaConfig and YogaNode respectively

Also added a positive test case. Didn't find the negative test case example. @[508947467:ianc] or @[759512522:emilsj], can you suggest a negative test case example.

Reviewed By: emilsjolander

Differential Revision: D7272067

fbshipit-source-id: e67e82eb057e4c7124904c715f9dca4dcfea21ea

java/com/facebook/yoga/YogaConfig.java

@@ -74,6 +74,19 @@ public class YogaConfig {
     jni_YGConfigSetUseLegacyStretchBehaviour(mNativePointer, useLegacyStretchBehaviour);
   }
 
+  private native void jni_YGConfigSetShouldDiffLayoutWithoutLegacyStretchBehaviour(
+      long nativePointer, boolean shouldDiffLayoutWithoutLegacyStretchBehaviour);
+  /**
+   * If this flag is set then yoga would diff the layout without legacy flag and would set a bool in
+   * YogaNode(mDoesLegacyStretchFlagAffectsLayout) with true if the layouts were different and false
+   * if not
+   */
+  public void setShouldDiffLayoutWithoutLegacyStretchBehaviour(
+      boolean shouldDiffLayoutWithoutLegacyStretchBehaviour) {
+    jni_YGConfigSetShouldDiffLayoutWithoutLegacyStretchBehaviour(
+        mNativePointer, shouldDiffLayoutWithoutLegacyStretchBehaviour);
+  }
+
   private native void jni_YGConfigSetLogger(long nativePointer, Object logger);
   public void setLogger(YogaLogger logger) {
     mLogger = logger;

java/com/facebook/yoga/YogaNode.java

@@ -82,6 +82,7 @@ public class YogaNode implements Cloneable {
   private int mLayoutDirection = 0;
   @DoNotStrip
   private boolean mHasNewLayout = true;
+  @DoNotStrip private boolean mDoesLegacyStretchFlagAffectsLayout = false;
 
   private native long jni_YGNodeNew();
   public YogaNode() {
@@ -136,6 +137,7 @@ public class YogaNode implements Cloneable {
     mMeasureFunction = null;
     mBaselineFunction = null;
     mData = null;
+    mDoesLegacyStretchFlagAffectsLayout = false;
 
     jni_YGNodeReset(mNativePointer);
   }
@@ -573,6 +575,10 @@ public class YogaNode implements Cloneable {
     return mHeight;
   }
 
+  public boolean getDoesLegacyStretchFlagAffectsLayout() {
+    return mDoesLegacyStretchFlagAffectsLayout;
+  }
+
   public float getLayoutMargin(YogaEdge edge) {
     switch (edge) {
       case LEFT: