fix quick fix infer parameter types from usage in js file

src/services/textChanges.ts

@@ -340,7 +340,9 @@ namespace ts.textChanges {
         }
 
         public insertJsdocCommentBefore(sourceFile: SourceFile, node: HasJSDoc, tag: JSDoc): void {
-            const fnStart = node.getStart(sourceFile);
+            const fnStart = node.kind === SyntaxKind.ArrowFunction
+                ? node.parent.parent.getStart(sourceFile)
+                : node.getStart(sourceFile);
             if (node.jsDoc) {
                 for (const jsdoc of node.jsDoc) {
                     this.deleteRange(sourceFile, {

tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts

@@ -0,0 +1,18 @@
+/// <reference path='fourslash.ts' />
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+// @noImplicitAny: true
+// @Filename: test.js
+
+////const foo = x => x.y + 1;
+
+verify.codeFix({
+  description: "Infer parameter types from usage",
+  index: 0,
+  newFileContent:
+`/**
+ * @param {{ y: number; }} x
+ */
+const foo = x => x.y + 1;`,
+});