Add support for parsing #void with Fasta.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/body_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 532fecac9a83af19a0030faa9eed344023cadfa0..9c2e8ef4720b7020f3ea8275b90df82dfe6aef09 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -2235,6 +2235,11 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
     push(new Operator(token.stringValue)..fileOffset = token.charOffset);
   }
 
+  @override
+  void handleSymbolVoid(Token token) {
+    logEvent("SymbolVoid");
+  }
+
   dynamic addCompileTimeError(int charOffset, String message) {
     return library.addCompileTimeError(charOffset, message, uri);
   }