fix: lower yield operator precedence

Author: davidbonnet

src/astring.js

@@ -80,11 +80,11 @@ export const EXPRESSIONS_PRECEDENCE = {
   UpdateExpression: 16,
   UnaryExpression: 15,
   AwaitExpression: 15,
-  YieldExpression: 15,
   BinaryExpression: 14,
   LogicalExpression: 13,
   ConditionalExpression: 4,
   AssignmentExpression: 3,
+  YieldExpression: 2,
   RestElement: 1,
 }
 

src/tests/fixtures/syntax/precedence.js

@@ -46,5 +46,7 @@ g = b + -+-a++;
   await f().a;
   yield 1;
   yield 1 + 2;
+  (yield 1) + (yield 2);
+  yield a = b;
   const c = yield 3;
 });