Port "Properly disallow yield in bodyless arrows"

internal/parser/parser.go

@@ -4324,6 +4324,7 @@ func (p *Parser) parseArrowFunctionExpressionBody(isAsync bool, allowReturnTypeI
 	}
 	saveContextFlags := p.contextFlags
 	p.setContextFlags(ast.NodeFlagsAwaitContext, isAsync)
+	p.setContextFlags(ast.NodeFlagsYieldContext, false)
 	node := p.parseAssignmentExpressionOrHigherWorker(allowReturnTypeInArrowFunction)
 	p.contextFlags = saveContextFlags
 	return node

testdata/baselines/reference/submodule/conformance/YieldExpression20_es6.errors.txt

@@ -0,0 +1,12 @@
+YieldExpression20_es6.ts(3,8): error TS1163: A 'yield' expression is only allowed in a generator body.
+
+
+==== YieldExpression20_es6.ts (1 errors) ====
+    function* test() {
+      return () => ({
+        b: yield 2, // error
+           ~~~~~
+!!! error TS1163: A 'yield' expression is only allowed in a generator body.
+      });
+    }
+