Make getAwaitedType private

Also, fix an additional baseline change.

Author: elibarzilay

src/compiler/types.ts

@@ -3421,6 +3421,7 @@ namespace ts {
         getWidenedType(type: Type): Type;
         /* @internal */
         getPromisedTypeOfPromise(promise: Type, errorNode?: Node): Type | undefined;
+        /* @internal */
         getAwaitedType(type: Type): Type | undefined;
         getReturnTypeOfSignature(signature: Signature): Type;
         /**

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -2035,7 +2035,6 @@ declare namespace ts {
         getBaseTypes(type: InterfaceType): BaseType[];
         getBaseTypeOfLiteralType(type: Type): Type;
         getWidenedType(type: Type): Type;
-        getAwaitedType(type: Type): Type | undefined;
         getReturnTypeOfSignature(signature: Signature): Type;
         getNullableType(type: Type, flags: TypeFlags): Type;
         getNonNullableType(type: Type): Type;

tests/baselines/reference/api/typescript.d.ts

@@ -2035,7 +2035,6 @@ declare namespace ts {
         getBaseTypes(type: InterfaceType): BaseType[];
         getBaseTypeOfLiteralType(type: Type): Type;
         getWidenedType(type: Type): Type;
-        getAwaitedType(type: Type): Type | undefined;
         getReturnTypeOfSignature(signature: Signature): Type;
         getNullableType(type: Type, flags: TypeFlags): Type;
         getNonNullableType(type: Type): Type;

tests/baselines/reference/asyncArrowFunction_allowJs.errors.txt

@@ -1,7 +1,7 @@
 tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(3,17): error TS2322: Type '0' is not assignable to type 'string'.
-tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(6,24): error TS1064: The return type of an async function or method must be the global Promise<T> type.
+tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(6,24): error TS1064: The return type of an async function or method must be the global Promise<T> type. Did you mean to write 'Promise<string>'?
 tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(7,23): error TS2322: Type '0' is not assignable to type 'string'.
-tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(10,24): error TS1064: The return type of an async function or method must be the global Promise<T> type.
+tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(10,24): error TS1064: The return type of an async function or method must be the global Promise<T> type. Did you mean to write 'Promise<string>'?
 tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(12,2): error TS2322: Type '0' is not assignable to type 'string'.
 tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(19,3): error TS2345: Argument of type '() => Promise<number>' is not assignable to parameter of type '() => string'.
   Type 'Promise<number>' is not assignable to type 'string'.
@@ -17,15 +17,15 @@ tests/cases/conformance/async/es2017/asyncArrowFunction/file.js(19,3): error TS2
     // Error (good)
     /** @type {function(): string} */
                            ~~~~~~
-!!! error TS1064: The return type of an async function or method must be the global Promise<T> type.
+!!! error TS1064: The return type of an async function or method must be the global Promise<T> type. Did you mean to write 'Promise<string>'?
     const b = async () => 0
                           ~
 !!! error TS2322: Type '0' is not assignable to type 'string'.
 
     // No error (bad)
     /** @type {function(): string} */
                            ~~~~~~
-!!! error TS1064: The return type of an async function or method must be the global Promise<T> type.
+!!! error TS1064: The return type of an async function or method must be the global Promise<T> type. Did you mean to write 'Promise<string>'?
     const c = async () => {
     	return 0
     	~~~~~~~~