Add row reverse tests for position

Summary: after looking into the issue described in facebook#1208 it seems to apply to position too, so adding tests to confirm

Reviewed By: NickGerleman

Differential Revision: D50154056

fbshipit-source-id: 64dd04ce3ad765526a547fe60b699b664f251c06

gentest/fixtures/YGFlexDirectionTest.html

@@ -144,3 +144,39 @@
   <div style="width: 10px;"></div>
   <div style="width: 10px;"></div>
 </div>
+
+<div id="flex_direction_row_reverse_pos_left" data-disabled="true" style="height: 100px; width: 100px; flex-direction: row-reverse; left: 100px;">
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+</div>
+
+<div id="flex_direction_row_reverse_pos_start" data-disabled="true" style="height: 100px; width: 100px; flex-direction: row-reverse; start: 100px;">
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+</div>
+
+<div id="flex_direction_row_reverse_pos_right" data-disabled="true" style="height: 100px; width: 100px; flex-direction: row-reverse; right: 100px;">
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+</div>
+
+<div id="flex_direction_row_reverse_pos_end" data-disabled="true" style="height: 100px; width: 100px; flex-direction: row-reverse; end: 100px;">
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+</div>
+
+<div id="flex_direction_column_reverse_pos_top" data-disabled="true" style="height: 100px; width: 100px; flex-direction: column-reverse; top: 100px;">
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+</div>
+
+<div id="flex_direction_column_reverse_pos_bottom" data-disabled="true" style="height: 100px; width: 100px; flex-direction: column-reverse; bottom: 100px;">
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+  <div style="width: 10px;"></div>
+</div>