Wrap some generated do expressions in parens (#5339)

packages/babel-generator/src/node/parentheses.js

@@ -46,6 +46,10 @@ export function ObjectExpression(node: Object, parent: Object, printStack: Array
   return isFirstInStatement(printStack, { considerArrow: true });
 }
 
+export function DoExpression(node: Object, parent: Object, printStack: Array<Object>): boolean {
+  return isFirstInStatement(printStack);
+}
+
 export function Binary(node: Object, parent: Object): boolean {
   if ((t.isCallExpression(parent) || t.isNewExpression(parent)) && parent.callee === node) {
     return true;

packages/babel-generator/test/fixtures/parentheses/do-expression/actual.js

@@ -0,0 +1,3 @@
+(do {
+  foo;
+});

packages/babel-generator/test/fixtures/parentheses/do-expression/expected.js

@@ -0,0 +1,3 @@
+(do {
+  foo;
+});