Support for AwaitExpression in unlinked expressions.

pkg/analyzer/lib/src/summary/summarize_const_expr.dart

Index: pkg/analyzer/lib/src/summary/summarize_const_expr.dart
diff --git a/pkg/analyzer/lib/src/summary/summarize_const_expr.dart b/pkg/analyzer/lib/src/summary/summarize_const_expr.dart
index f7e6911352860daa7af3f0640de86d39da73baa5..5a8702a99f7bad5baff07d16c9872b82015351e2 100644
--- a/pkg/analyzer/lib/src/summary/summarize_const_expr.dart
+++ b/pkg/analyzer/lib/src/summary/summarize_const_expr.dart
@@ -66,7 +66,7 @@ abstract class AbstractConstExprSerializer {
   bool isValidConst = true;
 
   /**
-   * See [UnlinkedExprBuilder.nmae].
+   * See [UnlinkedExprBuilder.name].
    */
   String name = null;
 
@@ -380,6 +380,10 @@ abstract class AbstractConstExprSerializer {
       isValidConst = false;
       _serialize(expr.expression);
       operations.add(UnlinkedExprOperation.throwException);
+    } else if (expr is AwaitExpression) {
+      isValidConst = false;
+      _serialize(expr.expression);
+      operations.add(UnlinkedExprOperation.await);
     } else {
       throw new StateError('Unknown expression type: $expr');
     }