Parse constructor field initializers with Fasta.

pkg/front_end/lib/src/fasta/source/diet_listener.dart

Index: pkg/front_end/lib/src/fasta/source/diet_listener.dart
diff --git a/pkg/front_end/lib/src/fasta/source/diet_listener.dart b/pkg/front_end/lib/src/fasta/source/diet_listener.dart
index defefc3e1a710fa7d248c79d2025b06586b10c77..825c468daa3417fb4341ce176badfe3cb2d48b56 100644
--- a/pkg/front_end/lib/src/fasta/source/diet_listener.dart
+++ b/pkg/front_end/lib/src/fasta/source/diet_listener.dart
@@ -495,6 +495,9 @@ class DietListener extends StackListener {
       bool allowAbstract = asyncModifier == AsyncMarker.Sync;
       parser.parseFunctionBody(token, isExpression, allowAbstract);
       var body = listener.pop();
+      if (listener.stack.length == 1) {

[ahe, 2017/04/06 14:25:21]

Could you explain what this is for?

[scheglov, 2017/04/06 15:51:55]

AstBuilder puts more data on the stack than the other parser.

[ahe, 2017/04/06 15:57:32]

Would it be possible to not do that? I'm trying to maintain the invariant that
the stack is null after parsing a function. This helps catch errors.

[scheglov, 2017/04/06 16:06:05]

The stack is empty after parsing a function.
But it is not empty after removing a function body.

[ahe, 2017/05/31 14:15:38]

What do you mean by removing a function body?

[scheglov, 2017/05/31 21:46:20]

The statement "var body = listener.pop();" removes a function body from the
stack.

[ahe, 2017/06/01 12:13:01]

I see. After calling parseFunctionBody, there should only be one thing on the
stack: the function body. That's the invariant that I'm maintaining here.

+        listener.pop(); // constructor initializers
+      }
       listener.checkEmpty(token.charOffset);
       listener.finishFunction(formals, asyncModifier, body);
     } on InputError {