Enable causal stacktrace 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 112ea43b8274b3f3e182cc2e99039834e589fcb6..6c0f0f10c721a957e9448e91ccdd2c38cc86842b 100644
--- a/pkg/kernel/lib/transformations/continuation.dart
+++ b/pkg/kernel/lib/transformations/continuation.dart
@@ -198,6 +198,8 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
       new VariableDeclaration(":async_op_then");
   final VariableDeclaration catchErrorContinuationVariable =
       new VariableDeclaration(":async_op_error");
+  final VariableDeclaration asyncStackTrace =
+      new VariableDeclaration(":async_stack_trace");
 
   LabeledStatement labeledBody;
 
@@ -215,6 +217,9 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
     // var :async_op_error;
     statements.add(catchErrorContinuationVariable);
 
+    // var :async_stack_trace;
+    statements.add(asyncStackTrace);
+
     // :async_op([:result, :exception, :stack_trace]) {
     //     modified <node.body>;
     // }
@@ -258,6 +263,13 @@ abstract class AsyncRewriterBase extends ContinuationRewriterBase {
         new VariableSet(
             catchErrorContinuationVariable, boundCatchErrorClosure));
     statements.add(catchErrorClosureVariableAssign);
+
+    // :async_stack_trace =  _asyncStackTraceHelper();

[kustermann, 2017/02/14 14:45:53]

nit: double space after =

[jensj, 2017/02/15 11:29:53]

Done.

+    final boundAsyncStackTrace = new StaticInvocation(
+        helper.asyncStackTraceHelper, new Arguments.empty());
+    final asyncStackTraceVariableAssign = new ExpressionStatement(
+        new VariableSet(asyncStackTrace, boundAsyncStackTrace));
+    statements.add(asyncStackTraceVariableAssign);
   }
 
   Statement buildWrappedBody() {
@@ -874,6 +886,7 @@ class HelperNodes {
   final Constructor streamIteratorConstructor;
   final Procedure asyncThenWrapper;
   final Procedure asyncErrorWrapper;
+  final Procedure asyncStackTraceHelper;
   final Procedure awaitHelper;
   final CoreTypes coreTypes;
 
@@ -891,6 +904,7 @@ class HelperNodes {
       this.streamControllerConstructor,
       this.asyncThenWrapper,
       this.asyncErrorWrapper,
+      this.asyncStackTraceHelper,
       this.awaitHelper,
       this.coreTypes);
 
@@ -973,6 +987,7 @@ class HelperNodes {
         findConstructor(streamControllerClass, ''),
         findProcedure(asyncLibrary, '_asyncThenWrapperHelper'),
         findProcedure(asyncLibrary, '_asyncErrorWrapperHelper'),
+        findProcedure(asyncLibrary, '_asyncStackTraceHelper'),
         findProcedure(asyncLibrary, '_awaitHelper'),
         new CoreTypes(program));
   }