The execution of an async* should only be scheduled when the stream is

pkg/compiler/lib/src/ssa/builder.dart

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index c4f78b8bd34fda31d9d4631002fd3c567e59fcdf..e5098ef8e84d58759c0acaef57b7212e1185d0b8 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -52,6 +52,8 @@ class SsaFunctionCompiler implements FunctionCompiler {
             backend.compiler.currentElement,
             streamHelper: backend.emitter.staticFunctionAccess(
                 backend.getStreamHelper()),
+            streamOfController: backend.emitter.staticFunctionAccess(
+                backend.getStreamOfController()),
             newController: backend.emitter.staticFunctionAccess(
                 backend.getASyncStarControllerConstructor()),
             safeVariableName: backend.namer.safeVariableName,