improve fasta export directive recovery

pkg/analyzer/test/generated/parser_test.dart

Index: pkg/analyzer/test/generated/parser_test.dart
diff --git a/pkg/analyzer/test/generated/parser_test.dart b/pkg/analyzer/test/generated/parser_test.dart
index 6eb0bfcf606957c62c5723a373c97397b4b9e7e6..21c9dbc246c6ab3eb7e4cdd2543f4fcf041b42ee 100644
--- a/pkg/analyzer/test/generated/parser_test.dart
+++ b/pkg/analyzer/test/generated/parser_test.dart
@@ -2645,9 +2645,32 @@ class Foo {
     CompilationUnit unit = parseCompilationUnit(
         "export '' class A {}", [ParserErrorCode.EXPECTED_TOKEN]);
     ExportDirective directive = unit.directives[0] as ExportDirective;
+    expect(directive.uri, isNotNull);
+    expect(directive.uri.stringValue, '');
+    expect(directive.uri.beginToken.isSynthetic, false);
+    expect(directive.uri.isSynthetic, false);
+    Token semicolon = directive.semicolon;
+    expect(semicolon, isNotNull);
+    expect(semicolon.isSynthetic, isTrue);
+    ClassDeclaration clazz = unit.declarations[0] as ClassDeclaration;
+    expect(clazz.name.name, 'A');
+  }
+
+  void test_expectedToken_uriAndSemicolonMissingAfterExport() {
+    CompilationUnit unit = parseCompilationUnit("export class A {}", [
+      ParserErrorCode.EXPECTED_STRING_LITERAL,
+      ParserErrorCode.EXPECTED_TOKEN,
+    ]);
+    ExportDirective directive = unit.directives[0] as ExportDirective;
+    expect(directive.uri, isNotNull);
+    expect(directive.uri.stringValue, '');
+    expect(directive.uri.beginToken.isSynthetic, true);
+    expect(directive.uri.isSynthetic, true);
     Token semicolon = directive.semicolon;
     expect(semicolon, isNotNull);
     expect(semicolon.isSynthetic, isTrue);
+    ClassDeclaration clazz = unit.declarations[0] as ClassDeclaration;
+    expect(clazz.name.name, 'A');
   }
 
   void test_expectedToken_semicolonMissingAfterExpression() {