Remove legacy layout diffing

Summary:
This removes some unused flags which will cause Yoga to layout every tree twice, then diffing the tree, reporting whether the whole tree is different. This is too expensive to run outside of local experimentation, but we have more nuanced ways to implement the `YGNodeLayoutAffectedByQuirk` I am wanting to add.

Changelog: [Internal]

Reviewed By: lunaleaps

Differential Revision: D42406917

fbshipit-source-id: b415ed02768f6b59de3a6fa90c60c750d56fd4b0

yoga/Yoga.h

@@ -147,7 +147,6 @@ WIN_EXPORT void YGNodeSetHasNewLayout(YGNodeRef node, bool hasNewLayout);
 YGNodeType YGNodeGetNodeType(YGNodeRef node);
 void YGNodeSetNodeType(YGNodeRef node, YGNodeType nodeType);
 WIN_EXPORT bool YGNodeIsDirty(YGNodeRef node);
-bool YGNodeLayoutGetDidUseLegacyFlag(YGNodeRef node);
 
 WIN_EXPORT void YGNodeStyleSetDirection(YGNodeRef node, YGDirection direction);
 WIN_EXPORT YGDirection YGNodeStyleGetDirection(YGNodeConstRef node);
@@ -290,7 +289,6 @@ WIN_EXPORT float YGNodeLayoutGetWidth(YGNodeRef node);
 WIN_EXPORT float YGNodeLayoutGetHeight(YGNodeRef node);
 WIN_EXPORT YGDirection YGNodeLayoutGetDirection(YGNodeRef node);
 WIN_EXPORT bool YGNodeLayoutGetHadOverflow(YGNodeRef node);
-bool YGNodeLayoutGetDidLegacyStretchFlagAffectLayout(YGNodeRef node);
 
 // Get the computed values for these nodes after performing layout. If they were
 // set using point values then the returned value will be the same as
@@ -315,9 +313,6 @@ WIN_EXPORT void YGAssertWithConfig(
 WIN_EXPORT void YGConfigSetPointScaleFactor(
     YGConfigRef config,
     float pixelsInPoint);
-void YGConfigSetShouldDiffLayoutWithoutLegacyStretchBehaviour(
-    YGConfigRef config,
-    bool shouldDiffLayout);
 
 // Yoga previously had an error where containers would take the maximum space
 // possible instead of the minimum like they are supposed to. In practice this