Update flex.js

Author: jacobp100

src/transforms/flex.js

@@ -6,6 +6,8 @@ const defaultFlexGrow = 1;
 const defaultFlexShrink = 1;
 const defaultFlexBasis = 0;
 
+const FLEX_BASIS_AUTO = {}; // Used for reference equality
+
 module.exports = (tokenStream) => {
   let flexGrow;
   let flexShrink;
@@ -14,8 +16,7 @@ module.exports = (tokenStream) => {
   if (tokenStream.matches(NONE)) {
     tokenStream.expectEmpty();
     return { $merge: { flexGrow: 0, flexShrink: 0 } };
-  } else if (tokenStream.matches(AUTO)) {
-    tokenStream.expectEmpty();
+  } else if (tokenStream.matches(AUTO) && !tokenStream.lookAhead().hasTokens()) {
     return { $merge: { flexGrow: 1, flexShrink: 1 } };
   }
 
@@ -32,6 +33,8 @@ module.exports = (tokenStream) => {
       }
     } else if (flexBasis === undefined && tokenStream.matches(LENGTH)) {
       flexBasis = tokenStream.lastValue;
+    } else if (flexBasis === undefined && tokenStream.matches(AUTO)) {
+      flexBasis = FLEX_BASIS_AUTO;
     } else {
       tokenStream.throw();
     }
@@ -45,5 +48,7 @@ module.exports = (tokenStream) => {
   if (flexShrink === undefined) flexShrink = defaultFlexShrink;
   if (flexBasis === undefined) flexBasis = defaultFlexBasis;
 
-  return { $merge: { flexGrow, flexShrink, flexBasis } };
+  return flexBasis !== FLEX_BASIS_AUTO
+    ? { $merge: { flexGrow, flexShrink, flexBasis } }
+    : { $merge: { flexGrow, flexShrink } };
 };