When translating analyzer/fasta token streams, match up begin/end tokens.

pkg/front_end/test/scanner_fasta_test.dart

Index: pkg/front_end/test/scanner_fasta_test.dart
diff --git a/pkg/front_end/test/scanner_fasta_test.dart b/pkg/front_end/test/scanner_fasta_test.dart
index f8704d3a4f5e6bff7ae62dfce3b6e64f88d19a74..ca3ccb09adc5c0a6bf570dd7fe0cccd56ba2881f 100644
--- a/pkg/front_end/test/scanner_fasta_test.dart
+++ b/pkg/front_end/test/scanner_fasta_test.dart
@@ -91,6 +91,22 @@ class ScannerTest_Fasta extends ScannerTestBase {
 
   @override
   @failingTest
+  void test_mismatched_closer() {
+    // TODO(paulberry,ahe): Fasta and analyzer recover this error differently.
+    // Figure out which recovery technique we want the front end to use.

[Paul Berry, 2017/02/13 22:38:59]

FWIW, my intuition is that Fasta's error recovery is better here, because when a
user is typing in a file, they are likely to type openers first and then close
them, so when there is a mismatch between an opener and a closer, it's probably
better to drop the opener.

[ahe, 2017/02/14 11:28:32]

That also has its downsides, but I have some ideas I want to try out in
pkg/front_end/lib/src/fasta/scanner/recover.dart in the future. I don't know
exactly when I'll find time to experiment with this, but feel free to ask me
more about it at any time.

+    super.test_mismatched_closer();
+  }
+
+  @override
+  @failingTest
+  void test_mismatched_opener() {
+    // TODO(paulberry,ahe): Fasta and analyzer recover this error differently.
+    // Figure out which recovery technique we want the front end to use.
+    super.test_mismatched_opener();
+  }
+
+  @override
+  @failingTest
   void test_scriptTag_withArgs() {
     // TODO(paulberry,ahe): script tags are needed by analyzer.
     super.test_scriptTag_withArgs();