Proper sequencing of _asyncStackTraceHelper in Kernel

pkg/kernel/lib/transformations/continuation.dart

Index: pkg/kernel/lib/transformations/continuation.dart
diff --git a/pkg/kernel/lib/transformations/continuation.dart b/pkg/kernel/lib/transformations/continuation.dart
index 632731756d68c6aaebf3d8dd38724047df8416e9..cce8f561545bc3868f5151863a16786620517ac9 100644
--- a/pkg/kernel/lib/transformations/continuation.dart
+++ b/pkg/kernel/lib/transformations/continuation.dart
@@ -215,6 +215,8 @@ class SyncStarFunctionRewriter extends ContinuationRewriterBase {
 abstract class AsyncRewriterBase extends ContinuationRewriterBase {
   final VariableDeclaration nestedClosureVariable =
       new VariableDeclaration(":async_op");
+  final VariableDeclaration stackTraceVariable =
+      new VariableDeclaration(":async_stack_trace");
   final VariableDeclaration thenContinuationVariable =
       new VariableDeclaration(":async_op_then");
   final VariableDeclaration catchErrorContinuationVariable =
@@ -230,6 +232,9 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
   void setupAsyncContinuations(List<Statement> statements) {
     expressionRewriter = new ExpressionLifter(this);
 
+    // var :async_stack_trace;
+    statements.add(stackTraceVariable);
+
     // var :async_op_then;
     statements.add(thenContinuationVariable);
 
@@ -269,6 +274,13 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
           ..fileOffset = enclosingFunction.parent.fileOffset;
     statements.add(closureFunction);
 
+    // :async_stack_trace = _asyncStackTraceHelper(asyncBody);
+    final stackTrace = new StaticInvocation(helper.asyncStackTraceHelper,
+        new Arguments(<Expression>[new VariableGet(nestedClosureVariable)]));
+    final stackTraceAssign = new ExpressionStatement(
+        new VariableSet(stackTraceVariable, stackTrace));
+    statements.add(stackTraceAssign);
+
     // :async_op_then = _asyncThenWrapperHelper(asyncBody);
     final boundThenClosure = new StaticInvocation(helper.asyncThenWrapper,
         new Arguments(<Expression>[new VariableGet(nestedClosureVariable)]));
@@ -905,6 +917,7 @@ class HelperNodes {
   final Constructor streamControllerConstructor;
   final Constructor syncIterableConstructor;
   final Constructor streamIteratorConstructor;
+  final Procedure asyncStackTraceHelper;
   final Procedure asyncThenWrapper;
   final Procedure asyncErrorWrapper;
   final Procedure awaitHelper;
@@ -923,6 +936,7 @@ class HelperNodes {
       this.streamIteratorConstructor,
       this.futureMicrotaskConstructor,
       this.streamControllerConstructor,
+      this.asyncStackTraceHelper,
       this.asyncThenWrapper,
       this.asyncErrorWrapper,
       this.awaitHelper,
@@ -942,6 +956,7 @@ class HelperNodes {
         coreTypes.streamIteratorDefaultConstructor,
         coreTypes.futureMicrotaskConstructor,
         coreTypes.asyncStarStreamControllerDefaultConstructor,
+        coreTypes.asyncStackTraceHelperProcedure,
         coreTypes.asyncThenWrapperHelperProcedure,
         coreTypes.asyncErrorWrapperHelperProcedure,
         coreTypes.awaitHelperProcedure,