properly handle shorthand JSX attributes in optimisation.react.inlineElements transformer - fixes #1309

src/babel/transformation/transformers/optimisation/react.inline-elements.js

@@ -57,7 +57,7 @@ export function JSXElement(node, parent, scope, file) {
     if (isJSXAttributeOfName(attr, "key")) {
       key = attr.value;
     } else {
-      pushProp(props.properties, attr.name, attr.value);
+      pushProp(props.properties, attr.name, attr.value || t.identifier("true"));
     }
   }
 

test/core/fixtures/transformation/optimisation.react.inline-elements/shorthand-attributes/actual.js

@@ -0,0 +1 @@
+<Foo bar />;

test/core/fixtures/transformation/optimisation.react.inline-elements/shorthand-attributes/expected.js

@@ -0,0 +1,10 @@
+"use strict";
+
+({
+  type: Foo,
+  ref: null,
+  props: babelHelpers.defaultProps(Foo.defaultProps, {
+    bar: true
+  }),
+  key: null
+});