gracefully handle default function

src/compiler/parser.ts

@@ -5986,6 +5986,9 @@ namespace ts {
                     case SyntaxKind.FunctionKeyword:
                     case SyntaxKind.ClassKeyword:
                     case SyntaxKind.EnumKeyword:
+                    // Include 'default' for error recovery.
+                    // falls through
+                    case SyntaxKind.DefaultKeyword:
                         return true;
 
                     // 'declare', 'module', 'namespace', 'interface'* and 'type' are all legal JavaScript identifiers;
@@ -6084,9 +6087,10 @@ namespace ts {
                 case SyntaxKind.ThrowKeyword:
                 case SyntaxKind.TryKeyword:
                 case SyntaxKind.DebuggerKeyword:
-                // 'catch' and 'finally' do not actually indicate that the code is part of a statement,
+                // 'default', 'catch' and 'finally' do not actually indicate that the code is part of a statement,
                 // however, we say they are here so that we may gracefully parse them and error later.
                 // falls through
+                case SyntaxKind.DefaultKeyword:
                 case SyntaxKind.CatchKeyword:
                 case SyntaxKind.FinallyKeyword:
                     return true;
@@ -6197,6 +6201,9 @@ namespace ts {
                 case SyntaxKind.StaticKeyword:
                 case SyntaxKind.ReadonlyKeyword:
                 case SyntaxKind.GlobalKeyword:
+                // Include 'default' for error recovery.
+                // falls through
+                case SyntaxKind.DefaultKeyword:
                     if (isStartOfDeclaration()) {
                         return parseDeclaration();
                     }

tests/baselines/reference/defaultKeywordWithoutExport2.errors.txt

@@ -1,12 +1,9 @@
-tests/cases/compiler/defaultKeywordWithoutExport2.ts(1,1): error TS1128: Declaration or statement expected.
-tests/cases/compiler/defaultKeywordWithoutExport2.ts(1,18): error TS1003: Identifier expected.
+tests/cases/compiler/defaultKeywordWithoutExport2.ts(1,1): error TS1029: 'export' modifier must precede 'default' modifier.
 
 
-==== tests/cases/compiler/defaultKeywordWithoutExport2.ts (2 errors) ====
+==== tests/cases/compiler/defaultKeywordWithoutExport2.ts (1 errors) ====
     default function () {
     ~~~~~~~
-!!! error TS1128: Declaration or statement expected.
-                     ~
-!!! error TS1003: Identifier expected.
+!!! error TS1029: 'export' modifier must precede 'default' modifier.
     
     }

tests/baselines/reference/defaultKeywordWithoutExport2.js

@@ -4,5 +4,5 @@ default function () {
 }
 
 //// [defaultKeywordWithoutExport2.js]
-function () {
+default function () {
 }

tests/baselines/reference/defaultKeywordWithoutExport2.symbols

@@ -1,5 +1,5 @@
 === tests/cases/compiler/defaultKeywordWithoutExport2.ts ===
 default function () {
-> : Symbol((Missing), Decl(defaultKeywordWithoutExport2.ts, 0, 7))
-
-}
+No type information for this code.
+No type information for this code.}
+No type information for this code.

tests/baselines/reference/defaultKeywordWithoutExport2.types

@@ -1,5 +1,5 @@
 === tests/cases/compiler/defaultKeywordWithoutExport2.ts ===
 default function () {
-> : () => void
-
-}
+No type information for this code.
+No type information for this code.}
+No type information for this code.