Revert "Enable causal stacktrace in kernel"

pkg/kernel/lib/transformations/continuation.dart

 // Copyright (c) 2016, 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 kernel.transformations.continuation;
 
 import 'dart:math' as math;
 
 import '../ast.dart';
 import '../core_types.dart';
@@ skipping 180 matching lines @@
   }
 }
 
 abstract class AsyncRewriterBase extends ContinuationRewriterBase {
   final VariableDeclaration nestedClosureVariable =
       new VariableDeclaration(":async_op");
   final VariableDeclaration thenContinuationVariable =
       new VariableDeclaration(":async_op_then");
   final VariableDeclaration catchErrorContinuationVariable =
       new VariableDeclaration(":async_op_error");
-  final VariableDeclaration asyncStackTrace =
-      new VariableDeclaration(":async_stack_trace");
 
   LabeledStatement labeledBody;
 
   ExpressionLifter expressionRewriter;
 
   AsyncRewriterBase(helper, enclosingFunction)
       : super(helper, enclosingFunction) {}
 
   void setupAsyncContinuations(List<Statement> statements) {
     expressionRewriter = new ExpressionLifter(this);
 
     // var :async_op_then;
     statements.add(thenContinuationVariable);
 
     // var :async_op_error;
     statements.add(catchErrorContinuationVariable);
 
-    // var :async_stack_trace;
-    statements.add(asyncStackTrace);
-
     // :async_op([:result, :exception, :stack_trace]) {
     //     modified <node.body>;
     // }
     final parameters = <VariableDeclaration>[
       expressionRewriter.asyncResult,
       new VariableDeclaration(':exception'),
       new VariableDeclaration(':stack_trace'),
     ];
     final function = new FunctionNode(buildWrappedBody(),
         positionalParameters: parameters,
@@ skipping 23 matching lines @@
     statements.add(thenClosureVariableAssign);
 
     // :async_op_error = _asyncErrorWrapperHelper(asyncBody);
     final boundCatchErrorClosure = new StaticInvocation(
         helper.asyncErrorWrapper,
         new Arguments(<Expression>[new VariableGet(nestedClosureVariable)]));
     final catchErrorClosureVariableAssign = new ExpressionStatement(
         new VariableSet(
             catchErrorContinuationVariable, boundCatchErrorClosure));
     statements.add(catchErrorClosureVariableAssign);
-
-    // :async_stack_trace = _asyncStackTraceHelper();
-    final boundAsyncStackTrace = new StaticInvocation(
-        helper.asyncStackTraceHelper, new Arguments.empty());
-    final asyncStackTraceVariableAssign = new ExpressionStatement(
-        new VariableSet(asyncStackTrace, boundAsyncStackTrace));
-    statements.add(asyncStackTraceVariableAssign);
   }
 
   Statement buildWrappedBody() {
     ++currentTryDepth;
     labeledBody = new LabeledStatement(null);
     labeledBody.body = visitDelimited(enclosingFunction.body)
       ..parent = labeledBody;
     --currentTryDepth;
 
     var exceptionVariable = new VariableDeclaration(":exception");
@@ skipping 596 matching lines @@
   final Class futureClass;
   final Class completerClass;
   final Procedure printProcedure;
   final Procedure completerConstructor;
   final Procedure futureMicrotaskConstructor;
   final Constructor streamControllerConstructor;
   final Constructor syncIterableConstructor;
   final Constructor streamIteratorConstructor;
   final Procedure asyncThenWrapper;
   final Procedure asyncErrorWrapper;
-  final Procedure asyncStackTraceHelper;
   final Procedure awaitHelper;
   final CoreTypes coreTypes;
 
   HelperNodes(
       this.asyncLibrary,
       this.coreLibrary,
       this.iteratorClass,
       this.futureClass,
       this.completerClass,
       this.printProcedure,
       this.completerConstructor,
       this.syncIterableConstructor,
       this.streamIteratorConstructor,
       this.futureMicrotaskConstructor,
       this.streamControllerConstructor,
       this.asyncThenWrapper,
       this.asyncErrorWrapper,
-      this.asyncStackTraceHelper,
       this.awaitHelper,
       this.coreTypes);
 
   factory HelperNodes.fromProgram(Program program) {
     Library findLibrary(String name) {
       Uri uri = Uri.parse(name);
       for (var library in program.libraries) {
         if (library.importUri == uri) return library;
       }
       throw 'Library "$name" not found';
@@ skipping 62 matching lines @@
         futureClass,
         completerClass,
         findProcedure(coreLibrary, 'print'),
         findFactoryConstructor(completerClass, 'sync'),
         findConstructor(syncIterableClass, ''),
         findConstructor(streamIteratorClass, ''),
         findFactoryConstructor(futureClass, 'microtask'),
         findConstructor(streamControllerClass, ''),
         findProcedure(asyncLibrary, '_asyncThenWrapperHelper'),
         findProcedure(asyncLibrary, '_asyncErrorWrapperHelper'),
-        findProcedure(asyncLibrary, '_asyncStackTraceHelper'),
         findProcedure(asyncLibrary, '_awaitHelper'),
         new CoreTypes(program));
   }
 }