Improve parsing of async and generator methods.

pkg/compiler/lib/src/parser/element_listener.dart

Index: pkg/compiler/lib/src/parser/element_listener.dart
diff --git a/pkg/compiler/lib/src/parser/element_listener.dart b/pkg/compiler/lib/src/parser/element_listener.dart
index 55e7e25605c0112dab0d4ad989b8c4ea96e028b5..2fbd225d247e3aaf4d919967bdfb8a3e05ec068e 100644
--- a/pkg/compiler/lib/src/parser/element_listener.dart
+++ b/pkg/compiler/lib/src/parser/element_listener.dart
@@ -741,6 +741,78 @@ class ElementListener extends Listener {
         errorCode = MessageKind.GENERIC;
         arguments = {"text": "Can't use '${token.lexeme}' as a name here."};
         break;
+
+      case ErrorKind.AbstractNotSync:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "Abstract methods can't use 'async', 'async*', or 'sync*'."
+        };
+        break;
+
+      case ErrorKind.SetterNotSync:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "Setters can't use 'async', 'async*', or 'sync*'."
+        };
+        break;
+
+      case ErrorKind.FactoryNotSync:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "Factories can't use 'async', 'async*', or 'sync*'."
+        };
+        break;
+
+      case ErrorKind.AwaitForNotAsync:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "Asynchronous for-loop can only be used "
+              "in 'async' or 'async*' methods."
+        };
+        break;
+
+      case ErrorKind.AsyncAsIdentifier:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "'async' can't be used as an identifier in "
+              "'async', 'async*', or 'sync*' methods."
+        };
+        break;
+
+      case ErrorKind.YieldNotGenerator:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "'yield' can only be used 'sync*' or 'async*' methods."

[Johnni Winther, 2017/03/17 13:34:10]

used 'sync*' -> used in 'sync*'

[ahe, 2017/03/17 14:00:16]

Done.

+        };
+        break;
+
+      case ErrorKind.YieldAsIdentifier:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "'yield' can't be used as an identifier in "
+              "'async', 'async*', or 'sync*' methods."
+        };
+        break;
+
+      case ErrorKind.GeneratorReturnsValue:
+        errorCode = MessageKind.GENERIC;
+        arguments = {"text": "'sync*' and 'async*' can't return a value."};
+        break;
+
+      case ErrorKind.AwaitNotAsync:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "'await' can only be used in 'async' or 'async*' methods."
+        };
+        break;
+
+      case ErrorKind.AwaitAsIdentifier:
+        errorCode = MessageKind.GENERIC;
+        arguments = {
+          "text": "'yield' can't be used as an identifier in "
+              "'async', 'async*', or 'sync*' methods."

[Johnni Winther, 2017/03/17 13:34:10]

'yield' -> 'await'

[ahe, 2017/03/17 14:00:15]

Done.

+        };
+        break;
     }
     SourceSpan span = reporter.spanFromToken(token);
     reportError(span, errorCode, arguments);