fix broken test case

Author: Kingwl

tests/cases/fourslash/codeFixAwaitInSyncFunction10.ts

@@ -5,9 +5,10 @@
 ////}
 
 verify.codeFix({
+    index: 3,
     description: "Add async modifier to containing function",
     newFileContent:
 `const f: () => Promise<number | string> = async () => {
     await Promise.resolve('foo');
-}`,
+}`
 });

tests/cases/fourslash/codeFixAwaitInSyncFunction11.ts

@@ -6,9 +6,10 @@
 
 // should not change type if it's incorrectly set
 verify.codeFix({
+    index: 3,
     description: "Add async modifier to containing function",
     newFileContent:
 `const f: string = async () => {
     await Promise.resolve('foo');
-}`,
+}`
 });

tests/cases/fourslash/codeFixAwaitInSyncFunction12.ts

@@ -5,6 +5,7 @@
 ////}
 
 verify.codeFix({
+    index: 1,
     description: "Add async modifier to containing function",
     newFileContent:
 `const f: () => Promise<Array<number | string>> = async function() {

tests/cases/fourslash/codeFixAwaitInSyncFunction13.ts

@@ -5,6 +5,7 @@
 ////}
 
 verify.codeFix({
+    index: 3,
     description: "Add async modifier to containing function",
     newFileContent:
 `const f: () => Promise<number | string> = async () => {

tests/cases/fourslash/codeFixAwaitInSyncFunction14.ts

@@ -5,6 +5,7 @@
 ////}
 
 verify.codeFix({
+    index: 1,
     description: "Add async modifier to containing function",
     newFileContent:
 `const f = async function(): Promise<number> {

tests/cases/fourslash/codeFixAwaitInSyncFunction15.ts

@@ -5,6 +5,7 @@
 ////}
 
 verify.codeFix({
+    index: 3,
     description: "Add async modifier to containing function",
     newFileContent:
 `const f = async (): Promise<number[]> => {

tests/cases/fourslash/codeFixAwaitInSyncFunction8.ts

@@ -5,6 +5,7 @@
 ////}
 
 verify.codeFix({
+    index: 1,
     description: "Add async modifier to containing function",
     newFileContent:
 `async function f(): Promise<number | string> {

tests/cases/fourslash/codeFixAwaitInSyncFunction9.ts

@@ -7,6 +7,7 @@
 ////}
 
 verify.codeFix({
+    index: 1,
     description: "Add async modifier to containing function",
     newFileContent:
 `class Foo {