remove old fasta missing exponent recovery

pkg/front_end/test/scanner_replacement_test.dart

Index: pkg/front_end/test/scanner_replacement_test.dart
diff --git a/pkg/front_end/test/scanner_replacement_test.dart b/pkg/front_end/test/scanner_replacement_test.dart
index 5d0a51a87d0897c2cd45a84f231900f8a3dfc3a5..824a1d3b6ea461875f0561516d86062d4418b66b 100644
--- a/pkg/front_end/test/scanner_replacement_test.dart
+++ b/pkg/front_end/test/scanner_replacement_test.dart
@@ -90,6 +90,25 @@ class ScannerTest_Replacement extends ScannerTestBase {
     ]);
   }
 
+  void test_double_error() {
+    String source = "3457e";
+    ErrorListener listener = new ErrorListener();
+    analyzer.Token token = scanWithListener(source, listener);
+    expect(token.type, analyzer.TokenType.DOUBLE);
+    expect(token.offset, 0);
+    expect(token.isSynthetic, isTrue);
+    // the invalid token is updated to be valid ...
+    expect(token.lexeme, source + "0");
+    // ... but the length does *not* include the additional character
+    // so as to be true to the original source.
+    expect(token.length, source.length);
+    expect(token.next.isEof, isTrue);
+    expect(listener.errors, hasLength(1));
+    TestError error = listener.errors[0];
+    expect(error.errorCode, ScannerErrorCode.MISSING_DIGIT);
+    expect(error.offset, source.length - 1);
+  }
+
   void test_lt() {
     // fasta does not automatically insert a closer for '<'
     // because it could be part of an expression rather than an opener