Add missing compile-time errors for async/await.

pkg/compiler/lib/src/resolution/members.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.resolution.members;
 
 import '../common.dart';
 import '../common/names.dart' show
     Selectors;
 import '../common/resolution.dart' show
@@ skipping 3669 matching lines @@
             node,
             MessageKind.RETURN_IN_GENERATOR,
             {'modifier': currentAsyncMarker});
       }
     }
     visit(node.expression);
     return const NoneResult();
   }
 
   ResolutionResult visitYield(Yield node) {
-    coreClasses.streamClass.ensureResolved(resolution);
-    coreClasses.iterableClass.ensureResolved(resolution);
+    if (!currentAsyncMarker.isYielding) {
+      reporter.reportErrorMessage(node, MessageKind.INVALID_YIELD);
+    }
+    if (currentAsyncMarker.isAsync) {
+      coreClasses.streamClass.ensureResolved(resolution);
+    } else {
+      coreClasses.iterableClass.ensureResolved(resolution);
+    }
     visit(node.expression);
     return const NoneResult();
   }
 
   ResolutionResult visitRedirectingFactoryBody(RedirectingFactoryBody node) {
     if (!enclosingElement.isFactoryConstructor) {
       reporter.reportErrorMessage(
           node, MessageKind.FACTORY_REDIRECTION_IN_NON_FACTORY);
       reporter.reportHintMessage(
           enclosingElement, MessageKind.MISSING_FACTORY_KEYWORD);
@@ skipping 116 matching lines @@
     return const NoneResult();
   }
 
   ResolutionResult visitThrow(Throw node) {
     registry.registerFeature(Feature.THROW_EXPRESSION);
     visit(node.expression);
     return const NoneResult();
   }
 
   ResolutionResult visitAwait(Await node) {
+    if (!currentAsyncMarker.isAsync) {
+      reporter.reportErrorMessage(node, MessageKind.INVALID_AWAIT);
+    }
     coreClasses.futureClass.ensureResolved(resolution);
     visit(node.expression);
     return const NoneResult();
   }
 
   ResolutionResult visitVariableDefinitions(VariableDefinitions node) {
     DartType type;
     if (node.type != null) {
       type = resolveTypeAnnotation(node.type);
     } else {
@@ skipping 505 matching lines @@
     }
     registry.registerTargetOf(node, target);
     return const NoneResult();
   }
 
   registerImplicitInvocation(Selector selector) {
     registry.registerDynamicUse(new DynamicUse(selector, null));
   }
 
   ResolutionResult visitAsyncForIn(AsyncForIn node) {
+    if (!currentAsyncMarker.isAsync) {
+      reporter.reportErrorMessage(
+          node.awaitToken, MessageKind.INVALID_AWAIT_FOR_IN);
+    }
     registry.registerFeature(Feature.ASYNC_FOR_IN);
     registry.registerDynamicUse(
         new DynamicUse(Selectors.current, null));
     registry.registerDynamicUse(
         new DynamicUse(Selectors.moveNext, null));
 
     visit(node.expression);
 
     Scope blockScope = new BlockScope(scope);
     visitForInDeclaredIdentifierIn(node.declaredIdentifier, node, blockScope);
@@ skipping 488 matching lines @@
     }
     return const NoneResult();
   }
 }
 
 /// Looks up [name] in [scope] and unwraps the result.
 Element lookupInScope(DiagnosticReporter reporter, Node node,
                       Scope scope, String name) {
   return Elements.unwrap(scope.lookup(name), reporter, node);
 }