Adding node type and moving rounding dependency to rely on that type

Summary: This diff adds node type definition to Yoga and moves rounding to rely on the node type. If the node has measure function we consider that node to be text node, otherwise we have default behavior.

Reviewed By: emilsjolander

Differential Revision: D5025107

fbshipit-source-id: a8d66e2f9c5d02ab080784cc474be583a09b92e2

enums.py

@@ -84,6 +84,10 @@ ENUMS = {
         'Vertical',
         'All',
     ],
+    'NodeType': [
+        'Default',
+        'Text',
+    ],
     'LogLevel': [
         'Error',
         'Warn',